import java.awt.Point;
import java.awt.geom.Line2D;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.security.GuardedObject;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
import java.io.InputStream;
import java.math.BigInteger;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */

public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;

        OutputStream outputStream = System.out;
        FastScanner in;
        PrintWriter out;

           in=new FastScanner(System.in);
            out=new PrintWriter(System.out);
        //in=new FastScanner(new FileInputStream(new File("C://Users//KANDARP//Desktop//coding_contest_creation (1).txt")));

        TaskC solver = new TaskC();
        long var=System.currentTimeMillis();
        solver.solve(1, in, out);
        /*if(System.getProperty("ONLINE_JUDGE")==null){
            out.println("["+(double)(System.currentTimeMillis()-var)/1000+"]");
        }*/
        out.close();
    }
}
class Pair {

    long x,y,index;
    long  r1,r2;
    HashMap<Double,Long> map=new HashMap<>();
    Pair(long x,long y,int index){
        this.x=x;
        this.y=y;
        this.index=index;
    }
    public String toString(){
        return this.x+" "+this.y+" ";
    }

}
class tupple{
    long x,y,z;
    ArrayList<String> list=new ArrayList<>();
    tupple(long x,long y,long z){
        this.x=x;
        this.y=y;
        this.z=z;
    }
    tupple(tupple cl){
        this.x=cl.x;
        this.y=cl.y;
        this.z=cl.z;
        this.list=cl.list;
    }
}
class Edge implements  Comparable<Edge>{
    int u;
    int v;
    int time;
    long cost;
    long wcost;
    public Edge(int u,int v,long cost,long wcost){
        this.u=u;
        this.v=v;
        this.cost=cost;
        this.wcost=wcost;
        time=Integer.MAX_VALUE;
    }
    public int other(int x){
        if(u==x)return v;
        return u;
    }
    @Override
    public int compareTo(Edge o) {
        // TODO Auto-generated method stub
        return Long.compare(cost, o.cost);
    }
}
class Ss{
    Integer a[]=new Integer[3];
    Ss(Integer a[]){
        this.a=a;

    }
    public int hashCode(){
        return a[0].hashCode()+a[1].hashCode()+a[2].hashCode();
    }
    public boolean equals(Object o){
        Ss x=(Ss)o;
        for(int i=0;i<3;i++){
            if(x.a[i]!=this.a[i]){
                return false;
            }
        }
        return true;

    }
}
class queary{
    int type;
    int l;
    int r;
    int index;
    queary(int type,int l,int r){
        this.type=type;
        this.l=l;
        this.r=r;
    }
}
class boat implements Comparable<boat>{
    int capacity;
    int index;
    boat(int capacity,int index)
    {
        this.capacity=capacity;
        this.index=index;
    }
    @Override
    public int compareTo(boat o) {
        // TODO Auto-generated method stub
        return this.capacity-o.capacity;
    }
}
class angle{
    double x,y,angle;
    int index;
    angle(int x,int y,double angle){
        this.x=x;
        this.y=y;
        this.angle=angle;
    }
}
class TaskC {
    static long mod=1000000007;
//    SegTree tree;
    //    int min[];
 /*   static int prime_len=1000010;
    static int prime[]=new int[prime_len];
    static long n_prime[]=new long[prime_len];
    static ArrayList<Integer> primes=new ArrayList<>();
    static{
        for(int i=2;i<=Math.sqrt(prime.length);i++){
            for(int j=i*i;j<prime.length;j+=i){

                prime[j]=i;

            }
        }
        for(int i=2;i<prime.length;i++){
            n_prime[i]=n_prime[i-1];
            if(prime[i]==0){
               n_prime[i]++;
            }

        }
    //  System.out.println("end");

    //  prime[0]=true;
    //  prime[1]=1;
    }
    /*
     *  long pp[]=new long[10000001];
            pp[0]=0;
            pp[1]=1;
            for(int i=2;i<pp.length;i++){
                if(prime[i]!=0){
                    int gcd=(int)greatestCommonDivisor(i/prime[i], prime[i]);
                    pp[i]=(pp[i/prime[i]]*pp[prime[i]]*gcd)/pp[(int)gcd];
                }
                else
                    pp[i]=i-1;
            }

}
     * */
    class Rmq {

		  int[] logTable;
		  int[][] rmq;
		  int[] a;

		  public Rmq(int[] a) {
		    this.a = a;
		    int n = a.length;

		    logTable = new int[n + 1];
		    for (int i = 2; i <= n; i++)
		      logTable[i] = logTable[i >> 1] + 1;

		    rmq = new int[logTable[n] + 1][n];

		    for (int i = 0; i < n; ++i)
		      rmq[0][i] = i;

		    for (int k = 1; (1 << k) < n; ++k) {
		      for (int i = 0; i + (1 << k) <= n; i++) {
		        int x = rmq[k - 1][i];
		        int y = rmq[k - 1][i + (1 << k - 1)];
		        rmq[k][i] = a[x] <= a[y] ? x : y;
		      }
		    }
		  }

		  public int minPos(int i, int j) {
		    int k = logTable[j - i];
		    int x = rmq[k][i];
		    int y = rmq[k][j - (1 << k) + 1];
		    return a[x] <= a[y] ? a[x] : a[y];
		  }

	}

   public void solve(int testNumber, FastScanner in, PrintWriter out) throws IOException {
	   int n=in.nextInt();
	   int k=in.nextInt();
	   String s=in.readString();
	   StringBuilder sb=new StringBuilder();
	   for(int i=0;i<n;i++){
		   if('z'-s.charAt(i)<=k){
			   k-='z'-s.charAt(i);
			   sb.append('z');
		   }
		   else {

			   sb.append((char)(s.charAt(i)+k));
			   k=0;
	//		   break;
		   }

	   }
	   if(k!=0){
		   out.println(-1);
	   }
	   else{
		   out.println(sb.toString());
	   }
   }

   static long greatestCommonDivisor (long m, long n){
       long x;
       long y;
       while(m%n != 0){
           x = n;
           y = m%n;
           m = x;
           n = y;
       }
       return n;
   }

 }

    /*
     * 	   long res[]=new long[m];
    	   int cl=1;
    	   int cr=0;
    	   for(int i=0;i<m;i++){
    		   int l=(int)q[i].x;
    		   int r=(int)q[i].y;
    		   while(cl>l){
    			   cl--;
    			   ans+=add(cl);

    		   }
    		   while(cl<l){
    			   ans-=remove(cl);
    			   cl++;

    		   }
    		   while(cr>r){
    			   ans-=remove(cr);
    			   cr--;
    		   }
    		   while(cr<r){
    			   cr++;
    			   ans+=add(cr);
    		   }
    		   res[(int)q[i].index]=ans;
    	   }
    	   for(int i=0;i<m;i++)
    		   out.println(res[i]);
     */

	   	 class SegmentTree2D {
          public  long max(int[][] t, int x1, int y1, int x2, int y2) {
            int n = t.length >> 1;
            x1 += n;
            x2 += n;
            int m = t[0].length >> 1;
            y1 += m;
            y2 += m;
            long res = 0;
            for (int lx = x1, rx = x2; lx <= rx; lx = (lx + 1) >> 1, rx = (rx - 1) >> 1)
              for (int ly = y1, ry = y2; ly <= ry; ly = (ly + 1) >> 1, ry = (ry - 1) >> 1) {
                if ((lx & 1) != 0 && (ly & 1) != 0) res = (res+ t[lx][ly]);
                if ((lx & 1) != 0 && (ry & 1) == 0) res = (res+ t[lx][ry]);
                if ((rx & 1) == 0 && (ly & 1) != 0) res =(res+t[rx][ly]);
                if ((rx & 1) == 0 && (ry & 1) == 0) res = (res+ t[rx][ry]);
              }
            return res;
          }

          public  void add(int[][] t, int x, int y, int value) {
            x += t.length >> 1;
            y += t[0].length >> 1;
            t[x][y] += value;
            for (int tx = x; tx > 0; tx >>= 1)
              for (int ty = y; ty > 0; ty >>= 1) {
                if (tx > 1) t[tx >> 1][ty] = (t[tx][ty]+t[tx ^ 1][ty]);
                if (ty > 1) t[tx][ty >> 1] = (t[tx][ty]+ t[tx][ty ^ 1]);
              }

//          for (int ty = y; ty > 1; ty >>= 1)
//            t[x][ty >> 1] = Math.max(t[x][ty], t[x][ty ^ 1]);
//          for (int tx = x; tx > 1; tx >>= 1)
//            for (int ty = y; ty > 0; ty >>= 1)
//              t[tx >> 1][ty] = Math.max(t[tx][ty], t[tx ^ 1][ty]);

//          for (int lx=x; lx> 0; lx >>= 1) {
//            if (lx > 1)
//              t[lx >> 1][y] = Math.max(t[lx][y], t[lx ^ 1][y]);
//            for (int ly = y; ly > 1; ly >>= 1)
//              t[lx][ly >> 1] = Math.max(t[lx][ly], t[lx][ly ^ 1]);
//          }
          }
    }

     class SegmentTree {

          // Modify the following 5 methods to implement your custom operations on the tree.
          // This example implements Add/Max operations. Operations like Add/Sum, Set/Max can also be implemented.
          long modifyOperation(long x, long y) {
            return  y;
          }

          // query (or combine) operation
          long queryOperation(long leftValue, long rightValue) {
            return (leftValue| rightValue);
          }

          long deltaEffectOnSegment(long delta, long segmentLength) {
            // Here you must write a fast equivalent of following slow code:
            // int result = delta;
            // for (int i = 1; i < segmentLength; i++) result = queryOperation(result, delta);
            // return result;
            return delta;
          }

          int getNeutralDelta() {
            return 0;
          }

          int getInitValue() {
            return 0;
          }

          // generic code
          int n;
          long[] value;
          long[] delta; // delta[i] affects value[i], delta[2*i+1] and delta[2*i+2]

          long joinValueWithDelta(long value, long delta) {
            if (delta == getNeutralDelta()) return value;
            return modifyOperation(value, delta);
          }

          long joinDeltas(long delta1, long delta2) {
            if (delta1 == getNeutralDelta()) return delta2;
            if (delta2 == getNeutralDelta()) return delta1;
            return modifyOperation(delta1, delta2);
          }

          void pushDelta(int root, int left, int right) {
            value[root] = joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            delta[2 * root + 1] = joinDeltas(delta[2 * root + 1], delta[root]);
            delta[2 * root + 2] = joinDeltas(delta[2 * root + 2], delta[root]);
            delta[root] = getNeutralDelta();
          }

          public SegmentTree(int n) {
            this.n = n;
            value = new long[4 * n];
            delta = new long[4 * n];
            init(0, 0, n - 1);
          }

          void init(int root, int left, int right) {
            if (left == right) {
              value[root] = getInitValue();
              delta[root] = getNeutralDelta();
            } else {
              int mid = (left + right) >> 1;
              init(2 * root + 1, left, mid);
              init(2 * root + 2, mid + 1, right);
              value[root] = queryOperation(value[2 * root + 1], value[2 * root + 2]);
              delta[root] = getNeutralDelta();
            }
          }

          public long query(int from, int to) {
            return query(from, to, 0, 0, n - 1);
          }

          long query(int from, int to, int root, int left, int right) {
            if (from == left && to == right)
              return joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid && to > mid)
              return queryOperation(
                  query(from, Math.min(to, mid), root * 2 + 1, left, mid),
                  query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right));
            else if (from <= mid)
              return query(from, Math.min(to, mid), root * 2 + 1, left, mid);
            else if (to > mid)
              return query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right);
            else
              throw new RuntimeException("Incorrect query from " + from + " to " + to);
          }

          public void modify(int from, int to, long delta) {
            modify(from, to, delta, 0, 0, n - 1);
          }

          void modify(int from, int to, long delta, int root, int left, int right) {
            if (from == left && to == right) {
              this.delta[root] = joinDeltas(this.delta[root], delta);
              return;
            }
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid)
              modify(from, Math.min(to, mid), delta, 2 * root + 1, left, mid);
            if (to > mid)
              modify(Math.max(from, mid + 1), to, delta, 2 * root + 2, mid + 1, right);
            value[root] = queryOperation(
                joinValueWithDelta(value[2 * root + 1], deltaEffectOnSegment(this.delta[2 * root + 1], mid - left + 1)),
                joinValueWithDelta(value[2 * root + 2], deltaEffectOnSegment(this.delta[2 * root + 2], right - mid)));
          }
    }

    class LcaSparseTable {

          int len;
          int[][] up;
          int[][] max;
          int[] tin;
          int[] tout;
          int time;
          int []lvel;

          void dfs(List<Integer>[] tree, int u, int p) {
            tin[u] = time++;
            lvel[u]=lvel[p]+1;
            up[0][u] = p;
            if(u!=p)
            //max[0][u]=weight(u,p);
            for (int i = 1; i < len; i++)
              {
                up[i][u] = up[i - 1][up[i - 1][u]];
                max[i][u]=Math.max(max[i-1][u],max[i-1][up[i-1][u]]);
              }
            for (int v : tree[u])
              if (v != p)
                dfs(tree, v, u);
            tout[u] = time++;
          }

          public LcaSparseTable(List<Integer>[] tree, int root) {
            int n = tree.length;
            len = 1;
            while ((1 << len) <= n) ++len;
            up = new int[len][n];
            max=new int[len][n];
            tin = new int[n];
            tout = new int[n];
            lvel=new int[n];
            lvel[root]=0;
            dfs(tree, root, root);
          }

          boolean isParent(int parent, int child) {
            return tin[parent] <= tin[child] && tout[child] <= tout[parent];
          }

          public int lca(int a, int b) {
            if (isParent(a, b))
              return a;
            if (isParent(b, a))
              return b;
            for (int i = len - 1; i >= 0; i--)
              if (!isParent(up[i][a], b))
                a = up[i][a];
            return up[0][a];
          }
          public long max(int a,int b){
              int lca=lca(a,b);
        //    System.out.println("LCA "+lca);
              long ans=0;
              int h=lvel[a]-lvel[lca];
            //  System.out.println("Height "+h);
              int index=0;
              while(h!=0){
                  if(h%2==1){
                      ans=Math.max(ans,max[index][a]);
                      a=up[index][a];
                  }
                  h/=2;
                  index++;
              }
              h=lvel[b]-lvel[lca];
             // System.out.println("Height "+h);

              index=0;
              while(h!=0){
                  if(h%2==1){
                      ans=Math.max(ans,max[index][b]);
                      b=up[index][b];
                  }
                  h/=2;
                  index++;
              }
              return ans;
          }

    static void dfs(List<Integer>[] graph, boolean[] used, List<Integer> res, int u,int parent,List<Integer> collection) {

        used[u] = true;
        Integer uu=new Integer(u);
        collection.add(uu);
        for (int v : graph[u]){
          if (!used[v]){
            dfs(graph, used, res, v,u,collection);

          }
          else if(collection.contains(v)){
              System.out.println("Impossible");
              System.exit(0);
          }
        }
        collection.remove(uu);
        res.add(u);
      }

      public static List<Integer> topologicalSort(List<Integer>[] graph) {
        int n = graph.length;
        boolean[] used = new boolean[n];
        List<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; i++)
          if (!used[i])
            dfs(graph, used, res, i,-1,new ArrayList<Integer>());
        Collections.reverse(res);
        return res;
      }

    static class pairs{
                String company,color;
                String type;
                boolean visit=false;
                pairs(String company,String color,String type){
                    this.company=company;
                    this.color=color;
                    this.type=type;
                }
            }

            static void dfs1(List<Integer>[] graph, boolean[] used, List<Integer> res, int u) {
            used[u] = true;
            for (int v : graph[u])
              if (!used[v])
                dfs1(graph, used, res, v);
            res.add(u);
          }

          public static List<Integer> topologicalSort1(List<Integer>[] graph) {
            int n = graph.length;
            boolean[] used = new boolean[n];
            List<Integer> res = new ArrayList<>();
            for (int i = n-1; i >0; i--)
              if (!used[i])
                dfs1(graph, used, res, i);
            Collections.reverse(res);
            return res;
          }

        int phi(int n) {
            int res = n;
            for (int i = 2; i * i <= n; ++i) {
                if (n % i == 0) {
                    while (n % i == 0) {
                        n /= i;
                    }
                    res -= res / i;
                }
            }
            if (n != 1) {
                res -= res / n;
            }
            return res;
        }
        long pow(long x,long y,long mod){
            if(y<=0){
                return 1;
            }
            if(y==1){
                return x%mod;
            }
            long temp=pow(x,y/2,mod);
            if(y%2==0){
                return (temp*temp)%mod;
            }
            else{
                return (((temp*temp)%mod)*x)%mod;
            }
        }

/*      long DP(int id,int mask){
            //System.out.println("hi"+dp[id][mask]+" "+id+" "+Integer.toBinaryString(mask));
            if(id==0 && mask==0){
                dp[0][mask]=1;
                return 1;
            }
            else if(id==0){
                dp[0][mask]=0;
                return 0;
            }
            if(dp[id][mask]!=-1){

                return dp[id][mask];
            }
            long ans=0;
            for(int i=0;i<n;i++){
                if((mask & (1<<i))!=0 && c[i][id]>=1){
                        ans+=DP(id-1,mask ^ (1 << i));
                        ans%=mod;
                }
            }
            ans+=DP(id-1,mask);
            ans%=mod;
            dp[id][mask]=ans;
            return ans;
        }*/
                long no_of_primes(long m,long n,long k){
                    long count=0,i,j;
                    int primes []=new int[(int)(n-m+2)];
                       if(m==1)    primes[0] = 1;
                        for(i=2; i<=Math.sqrt(n); i++)
                        {
                            j = (m/i);    j *= i;
                            if(j<m)
                                j+=i;
                            for(; j<=n; j+=i)
                             {
                                 if(j!=i)
                                    primes[(int)(j-m)] = 1;
                             }
                        }

                for(i=0; i<=n-m; i++)
                            if(primes[(int)i]==0 && (i-1)%k==0)
                                count++;
                return count;
                }
}
class SegTree {
    int n;
    long  t[];
    long mod=(long)(1000000007);
    SegTree(int n,long  t[]){
        this.n=n;
        this.t=t;
        build();
    }

    void build() {  // build the tree

        for (int i = n - 1; i > 0; --i)
            t[i]=(t[i<<1]|t[i<<1|1]);
    }

     void modify(int p, long value) {  // set value at position p
      for (t[p += n]+=value; p > 1; p >>= 1) t[p>>1] = (t[p]|t[p^1]);
    }

     long query(int l, int r) {  // sum on interval [l, r)
      long res=0;

      for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if ((l&1)!=0) res=Math.max(res,t[l++]);
            if ((r&1)!=0) res=Math.max(res,t[--r]);
          }
      return res;
    }

    //
//
//
}
class FastScanner
{

    private InputStream stream;
    private byte[] buf = new byte[8192];
    private int curChar;
    private int snumChars;
    private SpaceCharFilter filter;

    public FastScanner(InputStream stream) {
        this.stream = stream;
    }

    public int snext() {
        if (snumChars == -1)
            throw new InputMismatchException();
        if (curChar >= snumChars) {
            curChar = 0;
            try {
                snumChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (snumChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }
    public int nextInt() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        int res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }

    public long nextLong() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        long res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }

    public String readString() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        StringBuilder res = new StringBuilder();
        do {
            res.appendCodePoint(c);
            c = snext();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
    }
}
 class UF {

    private int[] parent;  // parent[i] = parent of i
    private byte[] rank;   // rank[i] = rank of subtree rooted at i (never more than 31)
    private int count;     // number of components
    public UF(int N) {
        if (N < 0) throw new IllegalArgumentException();
        count = N;
        parent = new int[N];
        rank = new byte[N];
        for (int i = 0; i < N; i++) {
            parent[i] = i;
            rank[i] = 0;
        }
    }

    public int find(int p) {
        if (p < 0 || p >= parent.length) throw new IndexOutOfBoundsException();
        while (p != parent[p]) {
            parent[p] = parent[parent[p]];    // path compression by halving
            p = parent[p];
        }
        return p;
    }
    public int count() {
        return count;
    }

    public boolean connected(int p, int q) {
        return find(p) == find(q);
    }

    public boolean union(int p, int q) {
        int rootP = find(p);
        int rootQ = find(q);
        if (rootP == rootQ) return false;

        // make root of smaller rank point to root of larger rank
        if      (rank[rootP] < rank[rootQ]) parent[rootP] = rootQ;
        else if (rank[rootP] > rank[rootQ]) parent[rootQ] = rootP;
        else {
            parent[rootQ] = rootP;
            rank[rootP]++;
        }
        count--;
        return true;
    }

}
 class MyArrayList {

    private int[] myStore;
    private int actSize = 0;

    public MyArrayList(){
        myStore = new int[2];
    }

    public int get(int index){
        if(index < actSize)
            return myStore[index];
         else
            throw new ArrayIndexOutOfBoundsException();
    }

    public void add(int obj){
        if(myStore.length-actSize <= 1)
            increaseListSize();
        myStore[actSize++] = obj;
    }

    public int size(){
        return actSize;
    }

    private void increaseListSize(){
        myStore = Arrays.copyOf(myStore, myStore.length*2);
    }
}


import java.awt.Point;
import java.awt.geom.Line2D;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileReader;
import java.io.OutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.security.GuardedObject;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Scanner;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;
import java.io.InputStream;
import java.math.BigInteger;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */

public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;

        OutputStream outputStream = System.out;
        FastScanner in;
        PrintWriter out;

           in=new FastScanner(System.in);
            out=new PrintWriter(System.out);
        //in=new FastScanner(new FileInputStream(new File("C://Users//KANDARP//Desktop//coding_contest_creation (1).txt")));

        TaskC solver = new TaskC();
        long var=System.currentTimeMillis();
        solver.solve(1, in, out);
        /*if(System.getProperty("ONLINE_JUDGE")==null){
            out.println("["+(double)(System.currentTimeMillis()-var)/1000+"]");
        }*/
        out.close();
    }
}
class Pair {

    long x,y,index;
    long  r1,r2;
    HashMap<Double,Long> map=new HashMap<>();
    Pair(long x,long y,int index){
        this.x=x;
        this.y=y;
        this.index=index;
    }
    public String toString(){
        return this.x+" "+this.y+" ";
    }

}
class tupple{
    long x,y,z;
    ArrayList<String> list=new ArrayList<>();
    tupple(long x,long y,long z){
        this.x=x;
        this.y=y;
        this.z=z;
    }
    tupple(tupple cl){
        this.x=cl.x;
        this.y=cl.y;
        this.z=cl.z;
        this.list=cl.list;
    }
}
class Edge implements  Comparable<Edge>{
    int u;
    int v;
    int time;
    long cost;
    long wcost;
    public Edge(int u,int v,long cost,long wcost){
        this.u=u;
        this.v=v;
        this.cost=cost;
        this.wcost=wcost;
        time=Integer.MAX_VALUE;
    }
    public int other(int x){
        if(u==x)return v;
        return u;
    }
    @Override
    public int compareTo(Edge o) {
        // TODO Auto-generated method stub
        return Long.compare(cost, o.cost);
    }
}
class Ss{
    Integer a[]=new Integer[3];
    Ss(Integer a[]){
        this.a=a;

    }
    public int hashCode(){
        return a[0].hashCode()+a[1].hashCode()+a[2].hashCode();
    }
    public boolean equals(Object o){
        Ss x=(Ss)o;
        for(int i=0;i<3;i++){
            if(x.a[i]!=this.a[i]){
                return false;
            }
        }
        return true;

    }
}
class queary{
    int type;
    int l;
    int r;
    int index;
    queary(int type,int l,int r){
        this.type=type;
        this.l=l;
        this.r=r;
    }
}
class boat implements Comparable<boat>{
    int capacity;
    int index;
    boat(int capacity,int index)
    {
        this.capacity=capacity;
        this.index=index;
    }
    @Override
    public int compareTo(boat o) {
        // TODO Auto-generated method stub
        return this.capacity-o.capacity;
    }
}
class angle{
    double x,y,angle;
    int index;
    angle(int x,int y,double angle){
        this.x=x;
        this.y=y;
        this.angle=angle;
    }
}
class TaskC {
    static long mod=1000000007;
//    SegTree tree;
    //    int min[];
 /*   static int prime_len=1000010;
    static int prime[]=new int[prime_len];
    static long n_prime[]=new long[prime_len];
    static ArrayList<Integer> primes=new ArrayList<>();
    static{
        for(int i=2;i<=Math.sqrt(prime.length);i++){
            for(int j=i*i;j<prime.length;j+=i){

                prime[j]=i;

            }
        }
        for(int i=2;i<prime.length;i++){
            n_prime[i]=n_prime[i-1];
            if(prime[i]==0){
               n_prime[i]++;
            }

        }
    //  System.out.println("end");

    //  prime[0]=true;
    //  prime[1]=1;
    }
    /*
     *  long pp[]=new long[10000001];
            pp[0]=0;
            pp[1]=1;
            for(int i=2;i<pp.length;i++){
                if(prime[i]!=0){
                    int gcd=(int)greatestCommonDivisor(i/prime[i], prime[i]);
                    pp[i]=(pp[i/prime[i]]*pp[prime[i]]*gcd)/pp[(int)gcd];
                }
                else
                    pp[i]=i-1;
            }

}
     * */
    class Rmq {

		  int[] logTable;
		  int[][] rmq;
		  int[] a;

		  public Rmq(int[] a) {
		    this.a = a;
		    int n = a.length;

		    logTable = new int[n + 1];
		    for (int i = 2; i <= n; i++)
		      logTable[i] = logTable[i >> 1] + 1;

		    rmq = new int[logTable[n] + 1][n];

		    for (int i = 0; i < n; ++i)
		      rmq[0][i] = i;

		    for (int k = 1; (1 << k) < n; ++k) {
		      for (int i = 0; i + (1 << k) <= n; i++) {
		        int x = rmq[k - 1][i];
		        int y = rmq[k - 1][i + (1 << k - 1)];
		        rmq[k][i] = a[x] <= a[y] ? x : y;
		      }
		    }
		  }

		  public int minPos(int i, int j) {
		    int k = logTable[j - i];
		    int x = rmq[k][i];
		    int y = rmq[k][j - (1 << k) + 1];
		    return a[x] <= a[y] ? a[x] : a[y];
		  }

	}

   public void solve(int testNumber, FastScanner in, PrintWriter out) throws IOException {
	   int n=in.nextInt();
	   int k=in.nextInt();
	   String s=in.readString();
	   StringBuilder sb=new StringBuilder();
	   for(int i=0;i<s.length();i++){

		   if(Math.max('z'-s.charAt(i),s.charAt(i)-'a')<=k ){

			   k-=Math.max('z'-s.charAt(i),s.charAt(i)-'a');
			   if('z'-s.charAt(i)>s.charAt(i)-'a'){
				   sb.append('z');
			   }
			   else{
				   sb.append('a');
			   }
		   }
		   else {
			   if(s.charAt(i)+k<='z')
			   sb.append((char)(s.charAt(i)+k));
			   else{
				   sb.append((char)(s.charAt(i)-k));
			   }
			   k=0;
	//		   break;
		   }

	   }
	   if(k!=0){
		   out.println(-1);
	   }
	   else{
		   out.println(sb.toString());
	   }
   }

   static long greatestCommonDivisor (long m, long n){
       long x;
       long y;
       while(m%n != 0){
           x = n;
           y = m%n;
           m = x;
           n = y;
       }
       return n;
   }

 }

    /*
     * 	   long res[]=new long[m];
    	   int cl=1;
    	   int cr=0;
    	   for(int i=0;i<m;i++){
    		   int l=(int)q[i].x;
    		   int r=(int)q[i].y;
    		   while(cl>l){
    			   cl--;
    			   ans+=add(cl);

    		   }
    		   while(cl<l){
    			   ans-=remove(cl);
    			   cl++;

    		   }
    		   while(cr>r){
    			   ans-=remove(cr);
    			   cr--;
    		   }
    		   while(cr<r){
    			   cr++;
    			   ans+=add(cr);
    		   }
    		   res[(int)q[i].index]=ans;
    	   }
    	   for(int i=0;i<m;i++)
    		   out.println(res[i]);
     */

	   	 class SegmentTree2D {
          public  long max(int[][] t, int x1, int y1, int x2, int y2) {
            int n = t.length >> 1;
            x1 += n;
            x2 += n;
            int m = t[0].length >> 1;
            y1 += m;
            y2 += m;
            long res = 0;
            for (int lx = x1, rx = x2; lx <= rx; lx = (lx + 1) >> 1, rx = (rx - 1) >> 1)
              for (int ly = y1, ry = y2; ly <= ry; ly = (ly + 1) >> 1, ry = (ry - 1) >> 1) {
                if ((lx & 1) != 0 && (ly & 1) != 0) res = (res+ t[lx][ly]);
                if ((lx & 1) != 0 && (ry & 1) == 0) res = (res+ t[lx][ry]);
                if ((rx & 1) == 0 && (ly & 1) != 0) res =(res+t[rx][ly]);
                if ((rx & 1) == 0 && (ry & 1) == 0) res = (res+ t[rx][ry]);
              }
            return res;
          }

          public  void add(int[][] t, int x, int y, int value) {
            x += t.length >> 1;
            y += t[0].length >> 1;
            t[x][y] += value;
            for (int tx = x; tx > 0; tx >>= 1)
              for (int ty = y; ty > 0; ty >>= 1) {
                if (tx > 1) t[tx >> 1][ty] = (t[tx][ty]+t[tx ^ 1][ty]);
                if (ty > 1) t[tx][ty >> 1] = (t[tx][ty]+ t[tx][ty ^ 1]);
              }

//          for (int ty = y; ty > 1; ty >>= 1)
//            t[x][ty >> 1] = Math.max(t[x][ty], t[x][ty ^ 1]);
//          for (int tx = x; tx > 1; tx >>= 1)
//            for (int ty = y; ty > 0; ty >>= 1)
//              t[tx >> 1][ty] = Math.max(t[tx][ty], t[tx ^ 1][ty]);

//          for (int lx=x; lx> 0; lx >>= 1) {
//            if (lx > 1)
//              t[lx >> 1][y] = Math.max(t[lx][y], t[lx ^ 1][y]);
//            for (int ly = y; ly > 1; ly >>= 1)
//              t[lx][ly >> 1] = Math.max(t[lx][ly], t[lx][ly ^ 1]);
//          }
          }
    }

     class SegmentTree {

          // Modify the following 5 methods to implement your custom operations on the tree.
          // This example implements Add/Max operations. Operations like Add/Sum, Set/Max can also be implemented.
          long modifyOperation(long x, long y) {
            return  y;
          }

          // query (or combine) operation
          long queryOperation(long leftValue, long rightValue) {
            return (leftValue| rightValue);
          }

          long deltaEffectOnSegment(long delta, long segmentLength) {
            // Here you must write a fast equivalent of following slow code:
            // int result = delta;
            // for (int i = 1; i < segmentLength; i++) result = queryOperation(result, delta);
            // return result;
            return delta;
          }

          int getNeutralDelta() {
            return 0;
          }

          int getInitValue() {
            return 0;
          }

          // generic code
          int n;
          long[] value;
          long[] delta; // delta[i] affects value[i], delta[2*i+1] and delta[2*i+2]

          long joinValueWithDelta(long value, long delta) {
            if (delta == getNeutralDelta()) return value;
            return modifyOperation(value, delta);
          }

          long joinDeltas(long delta1, long delta2) {
            if (delta1 == getNeutralDelta()) return delta2;
            if (delta2 == getNeutralDelta()) return delta1;
            return modifyOperation(delta1, delta2);
          }

          void pushDelta(int root, int left, int right) {
            value[root] = joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            delta[2 * root + 1] = joinDeltas(delta[2 * root + 1], delta[root]);
            delta[2 * root + 2] = joinDeltas(delta[2 * root + 2], delta[root]);
            delta[root] = getNeutralDelta();
          }

          public SegmentTree(int n) {
            this.n = n;
            value = new long[4 * n];
            delta = new long[4 * n];
            init(0, 0, n - 1);
          }

          void init(int root, int left, int right) {
            if (left == right) {
              value[root] = getInitValue();
              delta[root] = getNeutralDelta();
            } else {
              int mid = (left + right) >> 1;
              init(2 * root + 1, left, mid);
              init(2 * root + 2, mid + 1, right);
              value[root] = queryOperation(value[2 * root + 1], value[2 * root + 2]);
              delta[root] = getNeutralDelta();
            }
          }

          public long query(int from, int to) {
            return query(from, to, 0, 0, n - 1);
          }

          long query(int from, int to, int root, int left, int right) {
            if (from == left && to == right)
              return joinValueWithDelta(value[root], deltaEffectOnSegment(delta[root], right - left + 1));
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid && to > mid)
              return queryOperation(
                  query(from, Math.min(to, mid), root * 2 + 1, left, mid),
                  query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right));
            else if (from <= mid)
              return query(from, Math.min(to, mid), root * 2 + 1, left, mid);
            else if (to > mid)
              return query(Math.max(from, mid + 1), to, root * 2 + 2, mid + 1, right);
            else
              throw new RuntimeException("Incorrect query from " + from + " to " + to);
          }

          public void modify(int from, int to, long delta) {
            modify(from, to, delta, 0, 0, n - 1);
          }

          void modify(int from, int to, long delta, int root, int left, int right) {
            if (from == left && to == right) {
              this.delta[root] = joinDeltas(this.delta[root], delta);
              return;
            }
            pushDelta(root, left, right);
            int mid = (left + right) >> 1;
            if (from <= mid)
              modify(from, Math.min(to, mid), delta, 2 * root + 1, left, mid);
            if (to > mid)
              modify(Math.max(from, mid + 1), to, delta, 2 * root + 2, mid + 1, right);
            value[root] = queryOperation(
                joinValueWithDelta(value[2 * root + 1], deltaEffectOnSegment(this.delta[2 * root + 1], mid - left + 1)),
                joinValueWithDelta(value[2 * root + 2], deltaEffectOnSegment(this.delta[2 * root + 2], right - mid)));
          }
    }

    class LcaSparseTable {

          int len;
          int[][] up;
          int[][] max;
          int[] tin;
          int[] tout;
          int time;
          int []lvel;

          void dfs(List<Integer>[] tree, int u, int p) {
            tin[u] = time++;
            lvel[u]=lvel[p]+1;
            up[0][u] = p;
            if(u!=p)
            //max[0][u]=weight(u,p);
            for (int i = 1; i < len; i++)
              {
                up[i][u] = up[i - 1][up[i - 1][u]];
                max[i][u]=Math.max(max[i-1][u],max[i-1][up[i-1][u]]);
              }
            for (int v : tree[u])
              if (v != p)
                dfs(tree, v, u);
            tout[u] = time++;
          }

          public LcaSparseTable(List<Integer>[] tree, int root) {
            int n = tree.length;
            len = 1;
            while ((1 << len) <= n) ++len;
            up = new int[len][n];
            max=new int[len][n];
            tin = new int[n];
            tout = new int[n];
            lvel=new int[n];
            lvel[root]=0;
            dfs(tree, root, root);
          }

          boolean isParent(int parent, int child) {
            return tin[parent] <= tin[child] && tout[child] <= tout[parent];
          }

          public int lca(int a, int b) {
            if (isParent(a, b))
              return a;
            if (isParent(b, a))
              return b;
            for (int i = len - 1; i >= 0; i--)
              if (!isParent(up[i][a], b))
                a = up[i][a];
            return up[0][a];
          }
          public long max(int a,int b){
              int lca=lca(a,b);
        //    System.out.println("LCA "+lca);
              long ans=0;
              int h=lvel[a]-lvel[lca];
            //  System.out.println("Height "+h);
              int index=0;
              while(h!=0){
                  if(h%2==1){
                      ans=Math.max(ans,max[index][a]);
                      a=up[index][a];
                  }
                  h/=2;
                  index++;
              }
              h=lvel[b]-lvel[lca];
             // System.out.println("Height "+h);

              index=0;
              while(h!=0){
                  if(h%2==1){
                      ans=Math.max(ans,max[index][b]);
                      b=up[index][b];
                  }
                  h/=2;
                  index++;
              }
              return ans;
          }

    static void dfs(List<Integer>[] graph, boolean[] used, List<Integer> res, int u,int parent,List<Integer> collection) {

        used[u] = true;
        Integer uu=new Integer(u);
        collection.add(uu);
        for (int v : graph[u]){
          if (!used[v]){
            dfs(graph, used, res, v,u,collection);

          }
          else if(collection.contains(v)){
              System.out.println("Impossible");
              System.exit(0);
          }
        }
        collection.remove(uu);
        res.add(u);
      }

      public static List<Integer> topologicalSort(List<Integer>[] graph) {
        int n = graph.length;
        boolean[] used = new boolean[n];
        List<Integer> res = new ArrayList<>();
        for (int i = 0; i < n; i++)
          if (!used[i])
            dfs(graph, used, res, i,-1,new ArrayList<Integer>());
        Collections.reverse(res);
        return res;
      }

    static class pairs{
                String company,color;
                String type;
                boolean visit=false;
                pairs(String company,String color,String type){
                    this.company=company;
                    this.color=color;
                    this.type=type;
                }
            }

            static void dfs1(List<Integer>[] graph, boolean[] used, List<Integer> res, int u) {
            used[u] = true;
            for (int v : graph[u])
              if (!used[v])
                dfs1(graph, used, res, v);
            res.add(u);
          }

          public static List<Integer> topologicalSort1(List<Integer>[] graph) {
            int n = graph.length;
            boolean[] used = new boolean[n];
            List<Integer> res = new ArrayList<>();
            for (int i = n-1; i >0; i--)
              if (!used[i])
                dfs1(graph, used, res, i);
            Collections.reverse(res);
            return res;
          }

        int phi(int n) {
            int res = n;
            for (int i = 2; i * i <= n; ++i) {
                if (n % i == 0) {
                    while (n % i == 0) {
                        n /= i;
                    }
                    res -= res / i;
                }
            }
            if (n != 1) {
                res -= res / n;
            }
            return res;
        }
        long pow(long x,long y,long mod){
            if(y<=0){
                return 1;
            }
            if(y==1){
                return x%mod;
            }
            long temp=pow(x,y/2,mod);
            if(y%2==0){
                return (temp*temp)%mod;
            }
            else{
                return (((temp*temp)%mod)*x)%mod;
            }
        }

/*      long DP(int id,int mask){
            //System.out.println("hi"+dp[id][mask]+" "+id+" "+Integer.toBinaryString(mask));
            if(id==0 && mask==0){
                dp[0][mask]=1;
                return 1;
            }
            else if(id==0){
                dp[0][mask]=0;
                return 0;
            }
            if(dp[id][mask]!=-1){

                return dp[id][mask];
            }
            long ans=0;
            for(int i=0;i<n;i++){
                if((mask & (1<<i))!=0 && c[i][id]>=1){
                        ans+=DP(id-1,mask ^ (1 << i));
                        ans%=mod;
                }
            }
            ans+=DP(id-1,mask);
            ans%=mod;
            dp[id][mask]=ans;
            return ans;
        }*/
                long no_of_primes(long m,long n,long k){
                    long count=0,i,j;
                    int primes []=new int[(int)(n-m+2)];
                       if(m==1)    primes[0] = 1;
                        for(i=2; i<=Math.sqrt(n); i++)
                        {
                            j = (m/i);    j *= i;
                            if(j<m)
                                j+=i;
                            for(; j<=n; j+=i)
                             {
                                 if(j!=i)
                                    primes[(int)(j-m)] = 1;
                             }
                        }

                for(i=0; i<=n-m; i++)
                            if(primes[(int)i]==0 && (i-1)%k==0)
                                count++;
                return count;
                }
}
class SegTree {
    int n;
    long  t[];
    long mod=(long)(1000000007);
    SegTree(int n,long  t[]){
        this.n=n;
        this.t=t;
        build();
    }

    void build() {  // build the tree

        for (int i = n - 1; i > 0; --i)
            t[i]=(t[i<<1]|t[i<<1|1]);
    }

     void modify(int p, long value) {  // set value at position p
      for (t[p += n]+=value; p > 1; p >>= 1) t[p>>1] = (t[p]|t[p^1]);
    }

     long query(int l, int r) {  // sum on interval [l, r)
      long res=0;

      for (l += n, r += n; l < r; l >>= 1, r >>= 1) {
            if ((l&1)!=0) res=Math.max(res,t[l++]);
            if ((r&1)!=0) res=Math.max(res,t[--r]);
          }
      return res;
    }

    //
//
//
}
class FastScanner
{

    private InputStream stream;
    private byte[] buf = new byte[8192];
    private int curChar;
    private int snumChars;
    private SpaceCharFilter filter;

    public FastScanner(InputStream stream) {
        this.stream = stream;
    }

    public int snext() {
        if (snumChars == -1)
            throw new InputMismatchException();
        if (curChar >= snumChars) {
            curChar = 0;
            try {
                snumChars = stream.read(buf);
            } catch (IOException e) {
                throw new InputMismatchException();
            }
            if (snumChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }
    public int nextInt() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        int res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }

    public long nextLong() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = snext();
        }

        long res = 0;

        do {
            if (c < '0' || c > '9')
                throw new InputMismatchException();
            res *= 10;
            res += c - '0';
            c = snext();
        } while (!isSpaceChar(c));

        return res * sgn;
    }

    public String readString() {
        int c = snext();
        while (isSpaceChar(c))
            c = snext();
        StringBuilder res = new StringBuilder();
        do {
            res.appendCodePoint(c);
            c = snext();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    public boolean isSpaceChar(int c) {
        if (filter != null)
            return filter.isSpaceChar(c);
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    public interface SpaceCharFilter {
        public boolean isSpaceChar(int ch);
    }
}
 class UF {

    private int[] parent;  // parent[i] = parent of i
    private byte[] rank;   // rank[i] = rank of subtree rooted at i (never more than 31)
    private int count;     // number of components
    public UF(int N) {
        if (N < 0) throw new IllegalArgumentException();
        count = N;
        parent = new int[N];
        rank = new byte[N];
        for (int i = 0; i < N; i++) {
            parent[i] = i;
            rank[i] = 0;
        }
    }

    public int find(int p) {
        if (p < 0 || p >= parent.length) throw new IndexOutOfBoundsException();
        while (p != parent[p]) {
            parent[p] = parent[parent[p]];    // path compression by halving
            p = parent[p];
        }
        return p;
    }
    public int count() {
        return count;
    }

    public boolean connected(int p, int q) {
        return find(p) == find(q);
    }

    public boolean union(int p, int q) {
        int rootP = find(p);
        int rootQ = find(q);
        if (rootP == rootQ) return false;

        // make root of smaller rank point to root of larger rank
        if      (rank[rootP] < rank[rootQ]) parent[rootP] = rootQ;
        else if (rank[rootP] > rank[rootQ]) parent[rootQ] = rootP;
        else {
            parent[rootQ] = rootP;
            rank[rootP]++;
        }
        count--;
        return true;
    }

}
 class MyArrayList {

    private int[] myStore;
    private int actSize = 0;

    public MyArrayList(){
        myStore = new int[2];
    }

    public int get(int index){
        if(index < actSize)
            return myStore[index];
         else
            throw new ArrayIndexOutOfBoundsException();
    }

    public void add(int obj){
        if(myStore.length-actSize <= 1)
            increaseListSize();
        myStore[actSize++] = obj;
    }

    public int size(){
        return actSize;
    }

    private void increaseListSize(){
        myStore = Arrays.copyOf(myStore, myStore.length*2);
    }
}


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class C628C {

	public static void main(String[] args)throws Exception {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

		StringTokenizer st = new StringTokenizer(in.readLine());

		int n = Integer.valueOf(st.nextToken()) , k = Integer.valueOf(st.nextToken());

		String s = in.readLine();

		int max = 0;

		for(int i = 0;i < n;i ++)
			max += Math.max(s.charAt(i) - 'a','z' - s.charAt(i));

		if(max < k){
			out.write("-1");
			out.close();
			return;
		}

		for(int i = 0;i < n;i ++)
			if(s.charAt(i) - 'a'> 'z' - s.charAt(i)){
				if(s.charAt(i) - 'a' > k){
					out.write("" + (char)(s.charAt(i) - k));
					k = 0;
				}else{
					out.write("a");
					k -= s.charAt(i) - 'a';
				}
			}else{
				if('z' - s.charAt(i) > k){
					out.write("" + (char)(s.charAt(i) + k));
					k = 0;
				}else{
					out.write("z");
					k -= 'z' - s.charAt(i);
				}
			}

		out.close();
	}

}


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.StringTokenizer;

public class C628C {

	public static void main(String[] args)throws Exception {

		BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));

		StringTokenizer st = new StringTokenizer(in.readLine());

		int n = Integer.valueOf(st.nextToken()) , k = Integer.valueOf(st.nextToken());

		String s = in.readLine();

		int max = 0;

		for(int i = 0;i < n;i ++)
			max += Math.max(s.charAt(i) - 'z','z' - s.charAt(i));

		if(max < k){
			out.write("-1");
			out.close();
			return;
		}

		for(int i = 0;i < n;i ++)
			if(s.charAt(i) - 'a'> 'z' - s.charAt(i)){
				if(s.charAt(i) - 'a' > k){
					out.write("" + (char)(s.charAt(i) - k));
					k = 0;
				}else{
					out.write("a");
					k -= s.charAt(i) - 'a';
				}
			}else{
				if('z' - s.charAt(i) > k){
					out.write("" + (char)(s.charAt(i) + k));
					k = 0;
				}else{
					out.write("z");
					k -= 'z' - s.charAt(i);
				}
			}

		out.close();
	}

}


import java.util.Scanner;

public class C {

	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int k = scanner.nextInt();
		scanner.nextLine();
		String s = scanner.nextLine();

		String newS = "";
		for(int i = 0; i < n; i++) {
			char c = s.charAt(i);

			int max = Math.max(Math.abs(c - 'a'), Math.abs('z' - c));
			// Get most points
			if(k > max) {
			//	System.out.println(1);
				k -= max;
				newS += furtherTo('a', 'z', c);

			}
			// Get 0
			else if(k == 0) {
			//	System.out.println(2);
				newS += c;

			}
			// Get exact points
			else {
			//	System.out.println(3);
				if(isLetter((char) (c + k))) {
					newS += (char) (c + k);

				}
				else {
					newS += (char) (c - k);

				}
				k = 0;

			}

		}

		if(k > 0) {
			System.out.println(-1);
		}
		else {
			System.out.println(newS);
		}

	}

	private static char furtherTo(char first, char end, char current) {
		int f = Math.abs(first - current);
		int s = Math.abs(end - current);

		if(f > s) {
			return first;
		}
		return end;

	}

	private static boolean isLetter(char c) {
		return 'a' <= c && c <= 'z';

	}

}


import java.util.Scanner;

public class C {

	public static void main(String[] args) {

		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		int k = scanner.nextInt();
		scanner.nextLine();
		String s = scanner.nextLine();

		StringBuffer newS = new StringBuffer();
		for(int i = 0; i < n; i++) {
			char c = s.charAt(i);

			int max = Math.max(Math.abs(c - 'a'), Math.abs('z' - c));
			// Get most points
			if(k > max) {
			//	System.out.println(1);
				k -= max;
				newS.append(furtherTo('a', 'z', c));

			}
			// Get 0
			else if(k == 0) {
			//	System.out.println(2);
				newS.append(c);

			}
			// Get exact points
			else {
			//	System.out.println(3);
				if(isLetter((char) (c + k))) {
					newS.append((char) (c + k));

				}
				else {
					newS.append((char) (c - k));

				}
				k = 0;

			}

		}

		if(k > 0) {
			System.out.println(-1);
		}
		else {
			System.out.println(newS);
		}

	}

	private static char furtherTo(char first, char end, char current) {
		int f = Math.abs(first - current);
		int s = Math.abs(end - current);

		if(f > s) {
			return first;
		}
		return end;

	}

	private static boolean isLetter(char c) {
		return 'a' <= c && c <= 'z';

	}

}


import java.io.*;
import java.util.StringTokenizer;

/**
 * Created by peacefrog on 2/20/16.
 * 9:00 AM
 */
public class CF628C {
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
	PrintWriter out;
	long timeBegin, timeEnd;

	public void runIO() throws IOException {
		timeBegin = System.currentTimeMillis();

		InputStream inputStream;
		OutputStream outputStream;

		if (ONLINE_JUDGE) {
			inputStream = System.in;
			Reader.init(inputStream);
			outputStream = System.out;

			out = new PrintWriter(outputStream);
		} else {
			inputStream = new FileInputStream("/home/peacefrog/Dropbox/IdeaProjects/Problem Solving/input");
			Reader.init(inputStream);
			out = new PrintWriter(System.out);
		}
		solve();
		out.flush();
		out.close();
		timeEnd = System.currentTimeMillis();
		System.err.println("Time = " + (timeEnd - timeBegin));
	}

	/*
	 * Start Solution Here
	 */

	private void solve() throws IOException {
		int n = Reader.nextInt(), k = Reader.nextInt();
		char[] s = Reader.nextLine().toCharArray();
		char[] changed = new char[n];
		int save = k ,maxPossible = 0 ;
		for (int i = 0; i < n; i++) {
			if(('z'-s[i])< k) {
				changed[i]= 'z';
				k -= ('z'-s[i]);
			}
			else {
				changed[i] = (char) ((int)s[i]+k);
				k = 0;
			}

//			maxPossible+= ('z'- s[i]);

		}

		if( k != 0) out.println(-1);
		else out.println(changed);

	}

	public static void main(String[] args) throws IOException {
		new CF628C().runIO();
	}

	static class Reader {
		static BufferedReader reader;
		static StringTokenizer tokenizer;

		/**
		 * call this method to initialize reader for InputStream
		 */
		static void init(InputStream input) {
			reader = new BufferedReader(new InputStreamReader(input));
			tokenizer = new StringTokenizer("");
		}

		/**
		 * get next word
		 */
		static String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		static String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return "";
		}

		static int nextChar() throws IOException {
			return reader.read();
		}

		static int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		static long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		static double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		static long[] nextLongArray(int n) throws IOException {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}

			return arr;
		}

		static int[] nextIntArray(int n) throws IOException {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}
	}
}


import java.io.*;
import java.util.StringTokenizer;

/**
 * Created by peacefrog on 2/20/16.
 * 9:00 AM
 */
public class CF628C {
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
	PrintWriter out;
	long timeBegin, timeEnd;

	public void runIO() throws IOException {
		timeBegin = System.currentTimeMillis();

		InputStream inputStream;
		OutputStream outputStream;

		if (ONLINE_JUDGE) {
			inputStream = System.in;
			Reader.init(inputStream);
			outputStream = System.out;

			out = new PrintWriter(outputStream);
		} else {
			inputStream = new FileInputStream("/home/peacefrog/Dropbox/IdeaProjects/Problem Solving/input");
			Reader.init(inputStream);
			out = new PrintWriter(System.out);
		}
		solve();
		out.flush();
		out.close();
		timeEnd = System.currentTimeMillis();
		System.err.println("Time = " + (timeEnd - timeBegin));
	}

	/*
	 * Start Solution Here
	 */

	private void solve() throws IOException {
		int n = Reader.nextInt(), k = Reader.nextInt();
		char[] s = Reader.nextLine().toCharArray();
		char[] changed = new char[n];
		int save = k ,maxPossible = 0 ;
		for (int i = 0; i < n; i++) {
			if(('z'-s[i]) > Math.abs('a'-s[i])) {
				if (('z' - s[i]) < k) {
					changed[i] = 'z';
					k -= ('z' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] + k);
					k = 0;
				}
			}
			else {
				if (Math.abs(s[i]- 'a') < k) {
					changed[i] = 'z';
					k -= ('z' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] - k);
					k = 0;
				}
			}
//			maxPossible+= ('z'- s[i]);

		}

		if( k != 0) out.println(-1);
		else out.println(changed);

	}

	public static void main(String[] args) throws IOException {
		new CF628C().runIO();
	}

	static class Reader {
		static BufferedReader reader;
		static StringTokenizer tokenizer;

		/**
		 * call this method to initialize reader for InputStream
		 */
		static void init(InputStream input) {
			reader = new BufferedReader(new InputStreamReader(input));
			tokenizer = new StringTokenizer("");
		}

		/**
		 * get next word
		 */
		static String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		static String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return "";
		}

		static int nextChar() throws IOException {
			return reader.read();
		}

		static int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		static long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		static double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		static long[] nextLongArray(int n) throws IOException {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}

			return arr;
		}

		static int[] nextIntArray(int n) throws IOException {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}
	}
}


import java.io.*;
import java.util.StringTokenizer;

/**
 * Created by peacefrog on 2/20/16.
 * 9:00 AM
 */
public class CF628C {
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
	PrintWriter out;
	long timeBegin, timeEnd;

	public void runIO() throws IOException {
		timeBegin = System.currentTimeMillis();

		InputStream inputStream;
		OutputStream outputStream;

		if (ONLINE_JUDGE) {
			inputStream = System.in;
			Reader.init(inputStream);
			outputStream = System.out;

			out = new PrintWriter(outputStream);
		} else {
			inputStream = new FileInputStream("/home/peacefrog/Dropbox/IdeaProjects/Problem Solving/input");
			Reader.init(inputStream);
			out = new PrintWriter(System.out);
		}
		solve();
		out.flush();
		out.close();
		timeEnd = System.currentTimeMillis();
		System.err.println("Time = " + (timeEnd - timeBegin));
	}

	/*
	 * Start Solution Here
	 */

	private void solve() throws IOException {
		int n = Reader.nextInt(), k = Reader.nextInt();
		char[] s = Reader.nextLine().toCharArray();
		char[] changed = new char[n];
		int save = k ,maxPossible = 0 ;
		for (int i = 0; i < n; i++) {
			if(('z'-s[i]) > Math.abs('a'-s[i])) {
				if (('z' - s[i]) < k) {
					changed[i] = 'z';
					k -= ('z' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] + k);
					k = 0;
				}
			}
			else {
				if (Math.abs(s[i]- 'a') < k) {
					changed[i] = 'z';
					k -= Math.abs('a' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] - k);
					k = 0;
				}
			}
//			maxPossible+= ('z'- s[i]);

		}

		if( k != 0) out.println(-1);
		else out.println(changed);

	}

	public static void main(String[] args) throws IOException {
		new CF628C().runIO();
	}

	static class Reader {
		static BufferedReader reader;
		static StringTokenizer tokenizer;

		/**
		 * call this method to initialize reader for InputStream
		 */
		static void init(InputStream input) {
			reader = new BufferedReader(new InputStreamReader(input));
			tokenizer = new StringTokenizer("");
		}

		/**
		 * get next word
		 */
		static String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		static String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return "";
		}

		static int nextChar() throws IOException {
			return reader.read();
		}

		static int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		static long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		static double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		static long[] nextLongArray(int n) throws IOException {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}

			return arr;
		}

		static int[] nextIntArray(int n) throws IOException {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}
	}
}


import java.io.*;
import java.util.StringTokenizer;

/**
 * Created by peacefrog on 2/20/16.
 * 9:00 AM
 */
public class CF628C {
	final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE") != null;
	PrintWriter out;
	long timeBegin, timeEnd;

	public void runIO() throws IOException {
		timeBegin = System.currentTimeMillis();

		InputStream inputStream;
		OutputStream outputStream;

		if (ONLINE_JUDGE) {
			inputStream = System.in;
			Reader.init(inputStream);
			outputStream = System.out;

			out = new PrintWriter(outputStream);
		} else {
			inputStream = new FileInputStream("/home/peacefrog/Dropbox/IdeaProjects/Problem Solving/input");
			Reader.init(inputStream);
			out = new PrintWriter(System.out);
		}
		solve();
		out.flush();
		out.close();
		timeEnd = System.currentTimeMillis();
		System.err.println("Time = " + (timeEnd - timeBegin));
	}

	/*
	 * Start Solution Here
	 */

	private void solve() throws IOException {
		int n = Reader.nextInt(), k = Reader.nextInt();
		char[] s = Reader.nextLine().toCharArray();
		char[] changed = new char[n];
		for (int i = 0; i < n; i++) {
			if(('z'-s[i]) > Math.abs('a'-s[i])) {
				if (('z' - s[i]) < k) {
					changed[i] = 'z';
					k -= ('z' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] + k);
					k = 0;
				}
			}
			else {
				if (Math.abs(s[i]- 'a') < k) {
					changed[i] = 'a';
					k -= Math.abs('a' - s[i]);
				} else {
					changed[i] = (char) ((int) s[i] - k);
					k = 0;
				}
			}
//			maxPossible+= ('z'- s[i]);

		}

		if( k != 0) out.println(-1);
		else out.println(changed);

	}

	public static void main(String[] args) throws IOException {
		new CF628C().runIO();
	}

	static class Reader {
		static BufferedReader reader;
		static StringTokenizer tokenizer;

		/**
		 * call this method to initialize reader for InputStream
		 */
		static void init(InputStream input) {
			reader = new BufferedReader(new InputStreamReader(input));
			tokenizer = new StringTokenizer("");
		}

		/**
		 * get next word
		 */
		static String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}

		static String nextLine() {
			try {
				return reader.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return "";
		}

		static int nextChar() throws IOException {
			return reader.read();
		}

		static int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		static long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		static double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		static long[] nextLongArray(int n) throws IOException {
			long[] arr = new long[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextLong();
			}

			return arr;
		}

		static int[] nextIntArray(int n) throws IOException {
			int[] arr = new int[n];
			for (int i = 0; i < n; i++) {
				arr[i] = nextInt();
			}
			return arr;
		}
	}
}


import java.io.InputStreamReader;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.InputStream;
import java.math.BigInteger;
import java.util.ArrayList;
/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Erasyl Abenov
 *
 *
 */
public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
            try (PrintWriter out = new PrintWriter(outputStream)) {
                TaskB solver = new TaskB();
                solver.solve(1, in, out);
            }
    }
}
class TaskB {
    public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException{
        int n = in.nextInt();
        int k = in.nextInt();
        String s = in.next();
        if(k/25 > n){
            out.println(-1);
            return;
        }
        String ans = "";
        ArrayList<Character> ll = new ArrayList<>();
        for(int i = 0; i < n; ++i){
           if(k == 0){
               ll.add(s.charAt(i));
               continue;
           }
           int z = 'z' - s.charAt(i);
           int d = s.charAt(i) - 'a';
           char l = 'a';
           if(z > d){
               d = z;
               l = 'z';
           }
           if(k >= d){
               ll.add(l);
               k -= d;
               continue;
           }
           if(s.charAt(i) - k >= 'a') ll.add((char)(s.charAt(i) - k));
           else  ll.add((char)(s.charAt(i) + k));
           k = 0;
        }
        if(k > 0) out.println(-1);
        else{
            for(char c : ll) out.print(c);
        }
    }
}
class InputReader {
    private final BufferedReader reader;
    private StringTokenizer tokenizer;
    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }

    public String nextLine() {
        try {
            return reader.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(nextLine());
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }
    public BigInteger nextBigInteger(){
        return new BigInteger(next());
    }
    public long nextLong() {
        return Long.parseLong(next());
    }
    public double nextDouble() {
        return Double.parseDouble(next());
    }
}


import java.io.InputStreamReader;
import java.io.IOException;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.io.InputStream;
import java.math.BigInteger;
/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Erasyl Abenov
 *
 *
 */
public class Main {
    public static void main(String[] args) throws IOException {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
            try (PrintWriter out = new PrintWriter(outputStream)) {
                TaskB solver = new TaskB();
                solver.solve(1, in, out);
            }
    }
}
class TaskB {
    public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException{
        int n = in.nextInt();
        int k = in.nextInt();
        String s = in.next();
        for(int i = 0; i < n; ++i){
           int z = 'z' - s.charAt(i);
           int d = s.charAt(i) - 'a';
           char l = 'a';
           if(z > d){
               d = z;
               l = 'z';
           }
           if(k >= d){
               out.print(l);
               k -= d;
           }
           else{
               if(s.charAt(i) - '0' - k >= 'a') out.print((char)(s.charAt(i) - k));
               else out.print((char)(s.charAt(i) + k));
           }
        }
    }
}
class InputReader {
    private final BufferedReader reader;
    private StringTokenizer tokenizer;
    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }

    public String nextLine() {
        try {
            return reader.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(nextLine());
        }
        return tokenizer.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(next());
    }
    public BigInteger nextBigInteger(){
        return new BigInteger(next());
    }
    public long nextLong() {
        return Long.parseLong(next());
    }
    public double nextDouble() {
        return Double.parseDouble(next());
    }


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Codef{
    public static void main(String[] args) throws IOException{
        BufferedReader vod=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(vod.readLine());
        int n=Integer.parseInt(st.nextToken());
        int m=Integer.parseInt(st.nextToken());
        char ar[]=vod.readLine().toCharArray();
        int k=0;
        boolean p;
        StringBuilder s=new StringBuilder();
        for (int i=0; i<n; i++){
            int a=ar[i]-'a';
            int b='z'-ar[i];
            if (a>b) p=true; else p=false;
            if (Math.max(a, b)<m-k){
                k+=Math.max(a,b);
                if (p)
                    s.append('a');
                else
                    s.append('z');
            }
            else{
                int c=m-k;
                if (p)
                    s.append((char)(ar[i]-c));
                else
                    s.append((char)(ar[i]+c));
                k+=c;
            }
        }
        System.out.println(s);
    }
}


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Codef{
    public static void main(String[] args) throws IOException{
        BufferedReader vod=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st=new StringTokenizer(vod.readLine());
        int n=Integer.parseInt(st.nextToken());
        int m=Integer.parseInt(st.nextToken());
        char ar[]=vod.readLine().toCharArray();
        int k=0;
        boolean p;
        StringBuilder s=new StringBuilder();
        for (int i=0; i<n; i++){
            int a=ar[i]-'a';
            int b='z'-ar[i];
            if (a>b) p=true; else p=false;
            if (Math.max(a, b)<m-k){
                k+=Math.max(a,b);
                if (p)
                    s.append('a');
                else
                    s.append('z');
            }
            else{
                int c=m-k;
                if (p)
                    s.append((char)(ar[i]-c));
                else
                    s.append((char)(ar[i]+c));
                k+=c;
            }
        }
        if (m!=k)
            System.out.print(-1);
        else
            System.out.print(s);
    }
}


import java.io.*;
import java.util.*;

public class C {

	public static void main(String[] args) throws IOException {

		FastScanner qwe = new FastScanner(System.in);

		int n = qwe.nextInt();
		int k = qwe.nextInt();

		char[] ans = new char[n];
		char[] word = qwe.next().toCharArray();

		for (int i = 0; i < word.length; i++) {
			if( k >= word[i]-'a' && k >= 'z'-word[i]){
				if(word[i]-'a' >= 'z'-word[i]){
					ans[i] = 'a';
					k -= word[i]-'a';
				}
				else{
					ans[i] = 'z';
					k -= 'z'-word[i];
				}
			}
			else {

				if(word[i]-'a' >= 'z'-word[i]){
					ans[i] = (char)(word[i]-k);
					k = 0;
				}
				else{
					ans[i] = (char)(word[i]+k);
					k = 0;
				}
			}
		}

		if(k > 0)System.out.println(-1);
		else System.out.println(String.valueOf(ans));

	}

	static class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner(InputStream in) throws IOException{
			br = new BufferedReader(new InputStreamReader(in));
			st = new StringTokenizer(br.readLine().trim());
		}
		public FastScanner(File in) throws IOException{
			br = new BufferedReader(new FileReader(in));
			st = new StringTokenizer(br.readLine().trim());
		}
		public int numTokens() throws IOException {
			if(!st.hasMoreTokens()){
				st = new StringTokenizer(br.readLine().trim());
				return numTokens();
			}
			return st.countTokens();
		}
		public String next() throws IOException {
			if(!st.hasMoreTokens()){
				st = new StringTokenizer(br.readLine().trim());
				return next();
			}
			return st.nextToken();
		}
		public double nextDouble() throws IOException{
			return Double.parseDouble(next());
		}
		public float nextFloat() throws IOException{
			return Float.parseFloat(next());
		}
		public long nextLong() throws IOException{
			return Long.parseLong(next());
		}
		public int nextInt() throws IOException{
			return Integer.parseInt(next());
		}
		public String nextLine() throws IOException{
			return br.readLine().trim();
		}
	}

}


import java.io.*;
public class C {
    public static void main (String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] nums = reader.readLine().split(" ");
        int n = Integer.parseInt(nums[0]);
        int k = Integer.parseInt(nums[1]);
        String str = reader.readLine();
        char[] arr = str.toCharArray();

        for (int i = 0; i < arr.length; i++) {
            int fromA = arr[i] - 'a';
            int toZ = 'z' - arr[i];
            int dist;
            char next;
            if (fromA > toZ) {
                dist = fromA;
                next = 'a';
            }
            else {
                dist = toZ;
                next = 'z';
            }

            if (k > dist) {
                k -= dist;
                arr[i] = next;
            }
            else if (next == 'a') {
                arr[i] -= k;
                k = 0;
                break;
            }
            else {
                arr[i] += k;
                k = 0;
                break;
            }
        }

        if (k > 0) {
            System.out.println(-1);
        }
        else {
            System.out.println(arr);
        }
    }
}


import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{

	// split de array
	public static int[] readInts(String cad) {
		String read[] = cad.split(" ");
		int res[] = new int[read.length];
		for (int i = 0; i < read.length; i++) {
			res[i] = Integer.parseInt(read[i]);
		}
		return res;
	}

	public static void main(String[] args) throws IOException {
		long inicio = System.currentTimeMillis();
		StringBuilder out = new StringBuilder();
		BufferedReader in;
		File archivo = new File("entrada");
		if (archivo.exists())
			in = new BufferedReader(new FileReader(archivo));
		else
			in = new BufferedReader(new InputStreamReader(System.in));

		int arr[] = readInts(in.readLine());
		int k = arr[1];
		char s[] = in.readLine().toCharArray();

		long count = 0;
		for (int i = 0; i < s.length; i++) {
			count += Math.max(s[i] - 'a', 'z' - s[i]);
		}
		if (count < k) {
			out.append("-1\n");
		} else {
			for (int i = 0; i < s.length; i++) {
				int f = Math.max(s[i] - 'a', 'z' - s[i]);
				if (k - f >= 0) {
					if (s[i] - 'a' > 'z' - s[i]) {
						out.append('a');
						k -= s[i] - 'a';
					} else {
						out.append('z');
						k -= 'z' - s[i];
					}
				} else {
					if (k > 0) {
						if (s[i] - 'a' > 'z' - s[i]) {
							out.append((char) ('a' + f - k));
						} else {
							out.append((char) ('z' - (f - k)));
						}
						k = 0;
					} else {
						out.append(s[i]);
					}
				}
			}

		}
		System.out.print(out);
		if (archivo.exists())
			System.out.println("Tiempo transcurrido : " + (System.currentTimeMillis() - inicio) + " milisegundos.");
	}
}


import java.util.*;
import java.io.*;
public class Major {
public static void main(String [] args)throws Exception{
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	StringTokenizer st = new StringTokenizer(br.readLine());
	int n = Integer.parseInt(st.nextToken());
	int k = Integer.parseInt(st.nextToken());
	String str = br.readLine();
	StringBuilder sb = new StringBuilder();
	for(int i = 0;i < str.length();i++){
		int a = str.charAt(i) - 'a';
		int b = 'z' - str.charAt(i);
		if(a > b){
		  int t = Math.min(k,a);
		  sb.append((char)(str.charAt(i) - t));
		  k -= t;
		}
		else{
		  int t = Math.min(k,b);
		  sb.append((char)(str.charAt(i) + t));
		  k -= t;
		}
	}
	if(k > 0){
		System.out.print("-1");
		return;
	}
	System.out.print(sb.toString());
}
}


import java.awt.Point;
import java.io.*;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.util.*;
import static java.lang.Math.*;
import java.math.BigDecimal;

/**
 *
 * @author Mojtaba
 */
public class Main {

    public static void main(String[] args) throws IOException {
        MyScanner in = new MyScanner(System.in);
        //Scanner in = new Scanner(System.in);
        //Scanner in = new Scanner(new File("input.txt"));

        PrintWriter writer = new PrintWriter(new BufferedOutputStream(System.out));
        StringBuilder sb = new StringBuilder("");

        int n = in.nextInt();
        int k = in.nextInt();
        char[] a = in.next().toCharArray();
        char[] b = new char[a.length];
        for (int i = 0; i < a.length; i++) {
            char ch = a[i];
            int fa = abs(ch - 'a');
            int fz = abs(ch - 'z');
            int m = max(fa, fz);
            if (k == 0) {
                b[i] = a[i];
            } else if (k <= m) {
                if (m == fa) {
                    b[i] = (char) (ch - k);
                } else {
                    b[i] = (char) (ch + k);
                }
                k = 0;
            } else {
                k -= m;
                if (m == fa) {
                    b[i] = 'a';
                } else {
                    b[i] = 'z';
                }
            }
        }
        if (k != 0) {
            sb.append(-1);
        } else {
            for (int i = 0; i < b.length; i++) {
                sb.append(b[i]);
            }
        }

        writer.println(sb.toString().trim());
        writer.flush();
        in.close();
    }
}

class MyScanner {

    BufferedReader reader;
    StringTokenizer tokenizer;

    public MyScanner(InputStream stream) {
        this.reader = new BufferedReader(new InputStreamReader(stream));
    }

    public int nextInt() throws IOException {
        return Integer.parseInt(next());
    }

    public int[] nextIntegerArray(int n) throws IOException {
        int[] a = new int[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = nextInt();
        }
        return a;
    }

    public long[] nextLongArray(int n) throws IOException {
        long[] a = new long[n];
        for (int i = 0; i < a.length; i++) {
            a[i] = nextLong();
        }
        return a;
    }

    public int nextInt(int radix) throws IOException {
        return Integer.parseInt(next(), radix);
    }

    public long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    public long nextLong(int radix) throws IOException {
        return Long.parseLong(next(), radix);
    }

    public double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    public BigInteger nextBigInteger() throws IOException {
        return new BigInteger(next());
    }

    public BigInteger nextBigInteger(int radix) throws IOException {
        return new BigInteger(next(), radix);
    }

    public String next() throws IOException {
        if (tokenizer == null || !tokenizer.hasMoreTokens()) {
            tokenizer = new StringTokenizer(reader.readLine());
            return this.next();
        }
        return tokenizer.nextToken();
    }

    public void close() throws IOException {
        this.reader.close();
    }
}


import java.io.*;
import java.util.*;
public class C628 {
public static void main(String[] args) throws IOException {
	input.init(System.in);
	PrintWriter out = new PrintWriter(System.out);
	int n = input.nextInt(), k = input.nextInt();
	String s = input.next();
	char[] res = new char[n];
	int dist = 0;
	for(int i = 0; i<n; i++)
	{
		char c = s.charAt(i);
		if(c <= 'm') res[i] = (char) Math.min('z', c+k-dist);
		else res[i] = (char) Math.max('a', c-(k-dist));
		dist += Math.abs(c - res[i]);
	}
	out.println(dist == k ? new String(res) : -1);
	out.close();
}

public static class input {
	static BufferedReader reader;
	static StringTokenizer tokenizer;

	static void init(InputStream input) {
		reader = new BufferedReader(new InputStreamReader(input));
		tokenizer = new StringTokenizer("");
	}

	static String next() throws IOException {
		while (!tokenizer.hasMoreTokens())
			tokenizer = new StringTokenizer(reader.readLine());
		return tokenizer.nextToken();
	}

	static int nextInt() throws IOException {
		return Integer.parseInt(next());
	}

	static double nextDouble() throws IOException {
		return Double.parseDouble(next());
	}

	static long nextLong() throws IOException {
		return Long.parseLong(next());
	}
}
}


import java.util.*;
import java.io.*;

public class C {
    public static void main(String[] args) throws IOException {
	BufferedReader in =
	    new BufferedReader(new InputStreamReader(System.in));
	PrintWriter out =
	    new PrintWriter(new OutputStreamWriter(System.out));
	String[] nk = in.readLine().split(" ");
	int n = Integer.parseInt(nk[0]);
	int k = Integer.parseInt(nk[1]);
	char[] s = in.readLine().toCharArray();
	char[] t = new char[n];
	for (int i = 0; i < n; i++) {
	    if (k == 0) t[i] = s[i];
	    else {
		t[i] = getDist(s[i], Math.min(k, maxDist(s[i])));
		k -= getCharDist(t[i], s[i]);
	    }
	}
	if (k == 0) {
	    for (int i = 0; i < n; i++) {
		out.print(t[i]);
	    }
	    out.println();
	    out.close();
	} else {
	    out.println("-1");
	    out.close();
	}
    }

    static int getCharDist(char c, char d) {
	return Math.abs(c-d);
    }

    static int maxDist(char c) {
	return Math.max(c-'a', 'z'-c);
    }

    static char getDist(char c, int diff) {
	if (c+diff <= 'z') return (char)(c+diff);
	return (char)(c-diff);
    }
}


import java.util.*;
import java.io.*;

public class Main {
	public static void main(String[] args) {
		Scanner stdin = new Scanner(new BufferedInputStream(System.in));
		int n = stdin.nextInt();
		int k = stdin.nextInt();
		stdin.nextLine();
		String s = stdin.nextLine();
		char[] ss = s.toCharArray();
//		System.out.println(ss.length);
//		for (int i = 0; i < n; i++)
//			System.out.print(ss[i]);
		for (int i = 0; i < ss.length && k > 0; i++) {
			char c = 'z';
			if (c - ss[i] < ss[i] - 'a')
				c = 'a';
//			System.out.print("c = " + c);
			if (Math.abs(c - ss[i]) > k) {
				if (ss[i] + k > 'z') {
					ss[i] -= k;
				} else {
					ss[i] += k;
				}
				k = 0;
			} else {
				k -= Math.abs(c - ss[i]);
				ss[i] = c;
			}
//			System.out.print(ss[i]);
		}
//		System.out.println();
		if (k == 0)
			System.out.println(String.valueOf(ss));
		else
			System.out.println(-1);

	}
}


import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class P628C {
  InputStream is;
  PrintWriter out;
  String INPUT = "3 1000 hey";

  void solve() {
    int n = ni();
    int k = ni();
    String s = ns();
    char a[] = s.toCharArray();
    for (int i = 0; i < n && k > 0; i++) {
      int up = Math.abs(a[i] - 'a');
      int down = Math.abs(a[i] - 'z');
      if (up > down) {
        a[i] -= Math.min(k, up);
        k -=  Math.min(k, up);
      } else {
        a[i] += Math.min(k, down);
        k -= Math.min(k, down);
      }
    }
    if (k > 0) {
      System.out.println(-1);
    } else {
      System.out.println(new String(a));
    }
  }

  public static void main(String[] args) throws Exception {
    new P628C().run();
  }

  void run() throws Exception {
    is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
    out = new PrintWriter(System.out);

    long s = System.currentTimeMillis();
    solve();
    out.flush();
    tr(System.currentTimeMillis() - s + "ms");
  }

  private byte[] inbuf = new byte[1024];
  private int lenbuf = 0, ptrbuf = 0;

  private int readByte() {
    if (lenbuf == -1)
      throw new InputMismatchException();
    if (ptrbuf >= lenbuf) {
      ptrbuf = 0;
      try {
        lenbuf = is.read(inbuf);
      } catch (IOException e) {
        throw new InputMismatchException();
      }
      if (lenbuf <= 0)
        return -1;
    }
    return inbuf[ptrbuf++];
  }

  private boolean isSpaceChar(int c) {
    return !(c >= 33 && c <= 126);
  }

  private int skip() {
    int b;
    while ((b = readByte()) != -1 && isSpaceChar(b))
      ;
    return b;
  }

  private double nd() {
    return Double.parseDouble(ns());
  }

  private char nc() {
    return (char) skip();
  }

  private String ns() {
    int b = skip();
    StringBuilder sb = new StringBuilder();
    while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }

  private char[] ns(int n) {
    char[] buf = new char[n];
    int b = skip(), p = 0;
    while (p < n && !(isSpaceChar(b))) {
      buf[p++] = (char) b;
      b = readByte();
    }
    return n == p ? buf : Arrays.copyOf(buf, p);
  }

  private char[][] nm(int n, int m) {
    char[][] map = new char[n][];
    for (int i = 0; i < n; i++)
      map[i] = ns(m);
    return map;
  }

  private int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private int ni() {
    int num = 0, b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }

    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }

  private long nl() {
    long num = 0;
    int b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }

    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }

  private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

  private void tr(Object... o) {
    if (!oj)
      System.out.println(Arrays.deepToString(o));
  }
}


import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class P628C {
  InputStream is;
  PrintWriter out;
  String INPUT = "4 26 bear";

  void solve() {
    int n = ni();
    int k = ni();
    String s = ns();
    char a[] = s.toCharArray();
    for (int i = 0; i < n && k > 0; i++) {
      int up = Math.abs(a[i] - 'a');
      int down = Math.abs(a[i] - 'z');
      if (up > down) {
        a[i] -= Math.min(k, up);
        k -= up;
      } else {
        a[i] += Math.min(k, down);
        k -= down;
      }
    }
    System.out.println(new String(a));
  }

  public static void main(String[] args) throws Exception {
    new P628C().run();
  }

  void run() throws Exception {
    is = oj ? System.in : new ByteArrayInputStream(INPUT.getBytes());
    out = new PrintWriter(System.out);

    long s = System.currentTimeMillis();
    solve();
    out.flush();
    tr(System.currentTimeMillis() - s + "ms");
  }

  private byte[] inbuf = new byte[1024];
  private int lenbuf = 0, ptrbuf = 0;

  private int readByte() {
    if (lenbuf == -1)
      throw new InputMismatchException();
    if (ptrbuf >= lenbuf) {
      ptrbuf = 0;
      try {
        lenbuf = is.read(inbuf);
      } catch (IOException e) {
        throw new InputMismatchException();
      }
      if (lenbuf <= 0)
        return -1;
    }
    return inbuf[ptrbuf++];
  }

  private boolean isSpaceChar(int c) {
    return !(c >= 33 && c <= 126);
  }

  private int skip() {
    int b;
    while ((b = readByte()) != -1 && isSpaceChar(b))
      ;
    return b;
  }

  private double nd() {
    return Double.parseDouble(ns());
  }

  private char nc() {
    return (char) skip();
  }

  private String ns() {
    int b = skip();
    StringBuilder sb = new StringBuilder();
    while (!(isSpaceChar(b))) { // when nextLine, (isSpaceChar(b) && b != ' ')
      sb.appendCodePoint(b);
      b = readByte();
    }
    return sb.toString();
  }

  private char[] ns(int n) {
    char[] buf = new char[n];
    int b = skip(), p = 0;
    while (p < n && !(isSpaceChar(b))) {
      buf[p++] = (char) b;
      b = readByte();
    }
    return n == p ? buf : Arrays.copyOf(buf, p);
  }

  private char[][] nm(int n, int m) {
    char[][] map = new char[n][];
    for (int i = 0; i < n; i++)
      map[i] = ns(m);
    return map;
  }

  private int[] na(int n) {
    int[] a = new int[n];
    for (int i = 0; i < n; i++)
      a[i] = ni();
    return a;
  }

  private int ni() {
    int num = 0, b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }

    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }

  private long nl() {
    long num = 0;
    int b;
    boolean minus = false;
    while ((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'))
      ;
    if (b == '-') {
      minus = true;
      b = readByte();
    }

    while (true) {
      if (b >= '0' && b <= '9') {
        num = num * 10 + (b - '0');
      } else {
        return minus ? -num : num;
      }
      b = readByte();
    }
  }

  private boolean oj = System.getProperty("ONLINE_JUDGE") != null;

  private void tr(Object... o) {
    if (!oj)
      System.out.println(Arrays.deepToString(o));
  }
}


import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;

/**
 * Feb 19, 2016 | 4:18:25 PM
 *

 * Description
 *
 *

 *
 * @author Essiennta Emmanuel (colourfulemmanuel@gmail.com)
 */
public class ProblemC{

    String solve(String s, int rem){
        int max = 0;
        for (int i = s.length() - 1; i >= 0; i--)
            max += Math.max(s.charAt(i) - 'a', 'z' - s.charAt(i));
        if (rem > max)
            return null;
        int used = 0;
        char[] ans = new char[s.length()];
        for (int i = 0; i < ans.length; i++)
            ans[i] = s.charAt(i);
        for (int i = s.length() - 1; used != rem && i >= 0; i--){
            char ch = s.charAt(i);
            char base;
            if (ch - 'a' > 'z' - ch)
                base = 'a';
            else
                base = 'z';
            if (rem < Math.abs(base - ch)){
                if (base == 'a'){
                    ans[i] = (char)('a' + ((ch - 'a') - rem));
                }else{
                    ans[i] = (char)('z' - (('z' - ch) - rem));
                }
                rem = 0;
            }else{
                rem -= Math.abs(base - ch);
                ans[i] = base;
            }
        }
        return new String(ans);
    }

    public static void main(String[] args) throws IOException{
        PrintWriter out = new PrintWriter(new BufferedOutputStream(System.out));
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        String[] split = in.readLine().split(" ");
        int k = Integer.parseInt(split[1]);
        String s = in.readLine();
        String solve = new ProblemC().solve(s, k);
        out.println(solve == null ? -1 : solve);
        out.close();
        in.close();
    }
}


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class C {
	static int max(char c) {
		c -= 'a';
		return Math.max(25 - c, c);
	}

	public static void main(String[] args) throws IOException {
		Reader.init(System.in);
		PrintWriter pw=new PrintWriter(System.out);
		int n = Reader.nextInt();
		int k = Reader.nextInt();
		char c, d;
		int maxdist;
		String line = Reader.nextLine();
		StringBuilder sb = new StringBuilder();
		for (int i = 0; i < n; i++) {
			maxdist = max(line.charAt(i));
			if (k - maxdist >= 0) {
				k -= maxdist;
				c = (char) (line.charAt(i) + maxdist);
				d = (char) (line.charAt(i) - maxdist);
				if (Character.isLowerCase(c)) {
					sb.append(c);
				} else{
					sb.append(d);
				}
			} else {
				c = (char) (line.charAt(i) + k);
				d = (char) (line.charAt(i) - k);
				if (Character.isLowerCase(c)) {
					sb.append(c);
				} else
					sb.append(d);
				k=0;
			}
		}
		if(k!=0)
			System.out.println("-1");
		else {
			pw.println(sb.toString());
			pw.flush();
		}
	}
}

class Reader {
	static BufferedReader reader;
	static StringTokenizer tokenizer;

	/** call this method to initialize reader for InputStream */
	static void init(InputStream input) {
		reader = new BufferedReader(new InputStreamReader(input));
		tokenizer = new StringTokenizer("");
	}

	/** get next word */
	static String next() throws IOException {
		while (!tokenizer.hasMoreTokens()) {
			// TODO add check for eof if necessary
			tokenizer = new StringTokenizer(reader.readLine());
		}
		return tokenizer.nextToken();
	}

	static int nextInt() throws IOException {
		return Integer.parseInt(next());
	}

	static String nextLine() throws IOException {
		return reader.readLine();
	}

	static double nextDouble() throws IOException {
		return Double.parseDouble(next());
	}
}