#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define INF 10000000000099ll
int main()
{
	int n,k;
	cin>>n>>k;
	string str,ans="";
	cin>>str;
	if(k==0)
	{
		cout<<str;
		return 0;
	}
	int i=0;
	for(i=0;i<n;i++)
	{
		if(k==0)
			break;
		//cout<<k<<" ";
		int disA = abs(str[i]-'a');
		int disZ = abs(str[i]-'z');
		if(k > disA && k> disZ)
		{
			if(disA > disZ)
				ans+='a',k-=disA;
			else
				ans+='z',k-=disZ;
			//cout<<"a";
		}
		else if(disA > disZ)
		{
			ans+=(char)(str[i]-k);
			k=0;
			break;
		}
		else
		{
			ans+=(char)(str[i]+k);
			k=0;
			break;
		}
	}
	if(k>0)
	{
		cout<<"-1";
		return 0;
	}
	if(ans.size() < str.size())
	{
		for(int j=i+1;j<n;j++)
			ans+=str[j];
	}
	cout<<ans;
	return 0;
}


#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define INF 10000000000099ll
int main()
{
	int n,k;
	cin>>n>>k;
	string str,ans="";
	cin>>str;
	if(k==0)
	{
		cout<<str;
		return 0;
	}
	int i=0;
	for(i=0;i<n;i++)
	{
		if(k==0)
			break;
		cout<<k<<" ";
		int disA = abs(str[i]-'a');
		int disZ = abs(str[i]-'z');
		if(k > disA && k> disZ)
		{
			if(disA > disZ)
				ans+='a',k-=disA;
			else
				ans+='z',k-=disZ;
			//cout<<"a";
		}
		else if(disA > disZ)
		{
			ans+=(char)(str[i]-k);
			k=0;
			break;
		}
		else
		{
			ans+=(char)(str[i]+k);
			k=0;
			break;
		}
	}
	if(k>0)
	{
		cout<<"-1";
		return 0;
	}
	if(ans.size() < str.size())
	{
		for(int j=i+1;j<n;j++)
			ans+=str[j];
	}
	cout<<ans;
	return 0;
}


#include<bits/stdc++.h>
using namespace std;
#define ll long long int
#define INF 10000000000099ll
int main()
{
	int n,k;
	cin>>n>>k;
	string str,ans="";
	cin>>str;
	int i=0;
	for(i=0;i<n;i++)
	{
		if(k==0)
			break;
		//cout<<k<<" ";
		int disA = abs(str[i]-'a');
		int disZ = abs(str[i]-'z');
		if(k > disA && k> disZ)
		{
			if(disA > disZ)
				ans+='a',k-=disA;
			else
				ans+='z',k-=disZ;
			//cout<<"a";
		}
		else if(disA > disZ)
		{
			ans+=(char)(str[i]-k);
			k=0;
			break;
		}
		else
		{
			ans+=(char)(str[i]+k);
			k=0;
			break;
		}
	}
	if(k>0)
	{
		cout<<"-1";
		return 0;
	}
	if(ans.size() < str.size())
	{
		for(int j=i+1;j<n;j++)
			ans+=str[j];
	}
	cout<<ans;
	return 0;
}


#pragma comment(linker, " /stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define forn(i,n) for(int i = 0; i < n; ++i)
#define foe(i,n) for(int i = 1; i <= n; ++i)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mk make_pair
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define INF 99999999
#define x first
#define y second
#define sz(x) (int)(x).size()
const double EPS = 1e-16;
const int N = 2*(1e6);
const long long MOD = 1e9+7;
const int MAX_MEM = 1e8;
const int LOGN = 25;
using ll = long long;
using lli = long long int;
using pii = pair<int,int>;
using vi = vector<int>;
using vii = vector<pii>;
using ull = unsigned long long;
template < class T >
int valbit(T n, int idx){ return ((n >> idx) & 1);}
template < class T >
int setbit(T n, int idx) { return (n | (1 << idx));}
template < class T >
int xorbit(T n, int idx) {return (n ^ (1 << idx));}
template <class T>
using min_heap = priority_queue<T,vector<T>,greater<T>>;
#define reunique(v) v.resize(unique(v.begin(),v.end()) - v.begin())
template < class T >  int highbit(T x) {int t = 1; if(x >= t << 16) t <<= 16; if(x >= t << 8) t <<= 8; if(x >= t << 4) t <<= 4; if(x >= t << 2) t <<= 2; if(x >= t << 1) t <<= 1; return t;}
ll binpow(ll a, ll b)
{
	ll ret = 1;
	while(b)
	{
		if(b & 1) ret = ret * a;
		a = a * a;
		b >>= 1;
	}
	return ret;
}
int n,k,dist[N],test;
char s[N];
string ans;
int get(int l, int r)
{
	return dist[r] - dist[l-1];
}
int main()
{
	scanf("%d %d\n%s", &n,&k,s+1);
	int Q = k;
	for(int i = 1; i <= n; ++i){
		dist[i] = (int)'z' - (int)s[i];
		dist[i] += dist[i-1];
	}
	for(int i = 1; i <= n; ++i){
		int suffix = get(i+1,n);
		if(suffix > k)
			ans = ans + s[i];
		else{
			int add =  k - suffix;
			k = suffix;
			char c = s[i] + add;
			ans = ans + c;
		}
	}
	for(int i = 0; i < ans.size(); ++i){
		test += abs(ans[i] - s[i+1]);
	}
	if(test != Q) return cout << -1 << "\n",0;
	printf("%s",ans.c_str());
	return 0;
}


#pragma comment(linker, " /stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define forn(i,n) for(int i = 0; i < n; ++i)
#define foe(i,n) for(int i = 1; i <= n; ++i)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mk make_pair
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define INF 99999999
#define x first
#define y second
#define sz(x) (int)(x).size()
const double EPS = 1e-16;
const int N = 2*(1e6);
const long long MOD = 1e9+7;
const int MAX_MEM = 1e8;
const int LOGN = 25;
using ll = long long;
using lli = long long int;
using pii = pair<int,int>;
using vi = vector<int>;
using vii = vector<pii>;
using ull = unsigned long long;
template < class T >
int valbit(T n, int idx){ return ((n >> idx) & 1);}
template < class T >
int setbit(T n, int idx) { return (n | (1 << idx));}
template < class T >
int xorbit(T n, int idx) {return (n ^ (1 << idx));}
template <class T>
using min_heap = priority_queue<T,vector<T>,greater<T>>;
#define reunique(v) v.resize(unique(v.begin(),v.end()) - v.begin())
template < class T >  int highbit(T x) {int t = 1; if(x >= t << 16) t <<= 16; if(x >= t << 8) t <<= 8; if(x >= t << 4) t <<= 4; if(x >= t << 2) t <<= 2; if(x >= t << 1) t <<= 1; return t;}
ll binpow(ll a, ll b)
{
	ll ret = 1;
	while(b)
	{
		if(b & 1) ret = ret * a;
		a = a * a;
		b >>= 1;
	}
	return ret;
}
int n,k,dist[N],test;
char s[N];
string ans;
int get(int l, int r)
{
	return dist[r] - dist[l-1];
}
int main()
{
	scanf("%d %d\n%s", &n,&k,s+1);
	for(int i = 1; i <= n; ++i){
		dist[i] = (int)'z' - (int)s[i];
		dist[i] += dist[i-1];
	}
	for(int i = 1; i <= n; ++i){
		int suffix = get(i+1,n);
		if(suffix > k)
			ans = ans + s[i];
		else{
			int add =  k - suffix;
			k = suffix;
			char c = s[i] + add;
			ans = ans + c;
		}
	}
	for(int i = 0; i < ans.size(); ++i){
		test += abs(ans[i] - s[i+1]);
	}
	if(test != k) return cout << -1 << "\n",0;
	printf("%s",ans.c_str());
	return 0;
}


#pragma comment(linker, " /stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define forn(i,n) for(int i = 0; i < n; ++i)
#define foe(i,n) for(int i = 1; i <= n; ++i)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mk make_pair
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define INF 99999999
#define x first
#define y second
#define sz(x) (int)(x).size()
const double EPS = 1e-16;
const int N = 2*(1e6);
const long long MOD = 1e9+7;
const int MAX_MEM = 1e8;
const int LOGN = 25;
using ll = long long;
using lli = long long int;
using pii = pair<int,int>;
using vi = vector<int>;
using vii = vector<pii>;
using ull = unsigned long long;
template < class T >
int valbit(T n, int idx){ return ((n >> idx) & 1);}
template < class T >
int setbit(T n, int idx) { return (n | (1 << idx));}
template < class T >
int xorbit(T n, int idx) {return (n ^ (1 << idx));}
template <class T>
using min_heap = priority_queue<T,vector<T>,greater<T>>;
#define reunique(v) v.resize(unique(v.begin(),v.end()) - v.begin())
template < class T >  int highbit(T x) {int t = 1; if(x >= t << 16) t <<= 16; if(x >= t << 8) t <<= 8; if(x >= t << 4) t <<= 4; if(x >= t << 2) t <<= 2; if(x >= t << 1) t <<= 1; return t;}
ll binpow(ll a, ll b)
{
	ll ret = 1;
	while(b)
	{
		if(b & 1) ret = ret * a;
		a = a * a;
		b >>= 1;
	}
	return ret;
}
int n,k,dist[N];
char s[N];
string ans;
int get(int l, int r)
{
	return dist[r] - dist[l-1];
}
int main()
{
	scanf("%d %d\n%s", &n,&k,s+1);
	for(int i = 1; i <= n; ++i){
		dist[i] = (int)'z' - (int)s[i];
		dist[i] += dist[i-1];
	}
	if(dist[n] < k) return cout << -1 << "\n",0;
	for(int i = 1; i <= n; ++i){
		int suffix = get(i+1,n);
		if(suffix > k)
			ans = ans + s[i];
		else{
			int add =  k - suffix;
			k = suffix;
			char c = s[i] + add;
			ans = ans + c;
		}
	}
	printf("%s",ans.c_str());
	return 0;
}


#pragma comment(linker, " /stack:200000000")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/rope>
#define forn(i,n) for(int i = 0; i < n; ++i)
#define foe(i,n) for(int i = 1; i <= n; ++i)
#define all(x) (x).begin(),(x).end()
#define pb push_back
#define mk make_pair
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
#define INF 99999999
#define x first
#define y second
#define sz(x) (int)(x).size()
const double EPS = 1e-16;
const int N = 2*(1e6);
const long long MOD = 1e9+7;
const int MAX_MEM = 1e8;
const int LOGN = 25;
using ll = long long;
using lli = long long int;
using pii = pair<int,int>;
using vi = vector<int>;
using vii = vector<pii>;
using ull = unsigned long long;
template < class T >
int valbit(T n, int idx){ return ((n >> idx) & 1);}
template < class T >
int setbit(T n, int idx) { return (n | (1 << idx));}
template < class T >
int xorbit(T n, int idx) {return (n ^ (1 << idx));}
template <class T>
using min_heap = priority_queue<T,vector<T>,greater<T>>;
#define reunique(v) v.resize(unique(v.begin(),v.end()) - v.begin())
template < class T >  int highbit(T x) {int t = 1; if(x >= t << 16) t <<= 16; if(x >= t << 8) t <<= 8; if(x >= t << 4) t <<= 4; if(x >= t << 2) t <<= 2; if(x >= t << 1) t <<= 1; return t;}
ll binpow(ll a, ll b)
{
	ll ret = 1;
	while(b)
	{
		if(b & 1) ret = ret * a;
		a = a * a;
		b >>= 1;
	}
	return ret;
}
int n,k;
char s[N];
int main()
{
	scanf("%d %d\n%s", &n,&k,s);
	for(int i = 0; i < n; ++i){
		int dist = 0;
		char ans = s[i];
		for(char c = 'a'; c <= 'z'; ++c){
			int absdist = abs(s[i] - c);
			if(absdist <= k && absdist > dist){
				dist = absdist;
				ans = c;
			}
		}
		s[i] = ans;
		k -= dist;
	}
	if(k > 0) return cout << -1 << "\n",0;
	printf("%s\n",s);
	return 0;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int a = 'z'-ch[i];
		int b = ch[i]-'a';
		ch[i] = char(ch[i]+max(min(a, x), min(b, x)));
		x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int a = 'z'-ch[i];
		int b = ch[i]-'a';
		ch[i] = char(ch[i]+max(min(a, x), min(b, x)));
		x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int b = 'z'-ch[i];
		int a = 'a'-ch[i];
		//cout << a << ' ' << b << endl;
		if(abs(a) > b && abs(a) <= x){ch[i] = ch[i]+a;x+=a;}
		else if(b > a && b <= x){ch[i] = ch[i]+b;x-=b;}
		else {ch[i] = ch[i]+x; x = 0;}
		//x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int b = 'z'-ch[i];
		int a = 'a'-ch[i];
		//cout << a << ' ' << b << endl;
		if(abs(a) > b && abs(a) <= x && a != 0){ch[i] = ch[i]+a;x+=a;}
		else if(b > a && b <= x && b != 0){ch[i] = ch[i]+b;x-=b;}
		else if(char(ch[i]+x) > 'z'){ch[i] = ch[i]-x;x = 0;}
		else {ch[i] = ch[i]+x;x = 0;}
		//x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int b = 'z'-ch[i];
		int a = 'a'-ch[i];
		//cout << a << ' ' << b << endl;
		if(abs(a) > b && abs(a) <= x && a != 0){ch[i] = ch[i]+a;x+=a;}
		else if(b > a && b <= x && b != 0){ch[i] = ch[i]+b;x-=b;}
		else if(char(ch[i]+x) != 'z'){ch[i] = ch[i]-x;x = 0;}
		else {ch[i] = ch[i]+x;x = 0;}
		//x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int a = 'z'-ch[i];
		int b = 'a'-ch[i];
		if(abs(a) > b && abs(a) <= x){ch[i] = ch[i]+a;x+=a;}
		else if(b > a && b <= x){ch[i] = ch[i]+b;x-=b;}
		else {ch[i] = ch[i]+x; x = 0;}
		//x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include <bits/stdc++.h>

using namespace std;

int vis[500000];
long long  ans;
char t[5000][5000];

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int n, x;
	string ch;
	cin >> n;
	cin >> x;
	cin >> ch;
	for(int i = 0;i < n;i++){
		int b = 'z'-ch[i];
		int a = 'a'-ch[i];
		//cout << a << ' ' << b << endl;
		if(abs(a) > b && abs(a) <= x && a != 0){ch[i] = ch[i]+a;x+=a;}
		else if(b > a && b <= x && b != 0){ch[i] = ch[i]+b;x-=b;}
		else if(b < x){ch[i] = ch[i]-x;x = 0;}
		else {ch[i] = ch[i]+x;x = 0;}
		//x-=max(min(a, x), min(b, x));
		if(x == 0)break;
	}
	if(x)cout << -1 << endl;
	else cout << ch << endl;
	//cout << 'z'-'b' << endl;
}


#include<bits/stdc++.h>
#define ss second
#define ff first
#define pb push_back
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
const int siz = 1e5+5;
int n,k;string s;
int main()
{
   ios_base::sync_with_stdio(false); cin.tie(NULL);

   cin>>n>>k>>s;
   string ans;
   for(int i = 0;i<n;i++)
   {
       int c = s[i]-'a';
       int d = 25-c;
       if(d>c)
       {
           char t = s[i]+min(d,k); k-=min(k,d);
           ans+=t;
       }
       else
       {
           char t = s[i]+min(k,c); k-=min(k,c);
           ans+=t;
       }
   }
   if(k>0) return cout<<-1<<endl,0;
   cout<<ans<<endl;

}


#include<bits/stdc++.h>
#define ss second
#define ff first
#define pb push_back
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
const int siz = 1e5+5;
int n,k;string s;
int main()
{
   ios_base::sync_with_stdio(false); cin.tie(NULL);

   cin>>n>>k>>s;
   string ans;
   for(int i = 0;i<n;i++)
   {
       int c = s[i]-'a';
       int d = min(k,25-c); k-=d;
       char t = s[i]+d;
       ans+=t;
   }
   if(k>0) return cout<<-1<<endl,0;
   cout<<ans<<endl;

}


#include<bits/stdc++.h>
#define ss second
#define ff first
#define pb push_back
using namespace std;
typedef long long ll;
const int mod = 1e9+7;
const int siz = 1e5+5;
int n,k;string s;
int main()
{
   ios_base::sync_with_stdio(false); cin.tie(NULL);

   cin>>n>>k>>s;
   string ans;
   for(int i = 0;i<n;i++)
   {
       int c = s[i]-'a';
       int d = 25-c;
       if(d>c)
       {
           char t = s[i]+min(d,k); k-=min(k,d);
           ans+=t;
       }
       else
       {
           char t = s[i]-min(k,c); k-=min(k,c);
           ans+=t;
       }
   }
   if(k>0) return cout<<-1<<endl,0;
   cout<<ans<<endl;

}


#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 100100;

int main()
{
    int  n,k;
     char s[N];
    scanf("%d%d", &n, &k);
	scanf("%s", s);
	char t[N];
    for(int i=0;i<n;i++)
    {

        int x=int(s[i]-'a');
        int y=25-x;
        if(x>y)
        {
            int d=min(x,k);
           t[i]=char(s[i]-d);
           k-=d;

        }
        else
        {
            int d=min(y,k);
            t[i]=char(s[i]+d);
            k-=d;
        }
    }

    if(k!=0)
    {
        printf("-1");
        return 0;
    }
//    puts(ans); */
t[n]=0;
puts(t);
 //  cout<<s<<endl;
}


#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main()
{
    int  n,k;
    scanf("%d %d",&n,&k);
    string s;
  //  scanf("%s",&s);
     cin>>s;
    for(ll i=0;i<n;i++)
    {
        if(k==0)
        {
            break;
        }
        ll x=s[i]-'a';
        if(x==1)
        {
            if(k>=25)
            {
                s[i]='z';
                k-=25;
            }
            else
            {
                ll p=x+k;
                s[i]=p+'a';
                k=0;
            }
            continue;
        }
        if(x==25)
        {
            if(k>=25)
            {
                s[i]='a';
                k-=25;
            }
            else
            {
                ll p=x-k;
                s[i]=p+'a';
                k=0;
            }
            continue;
        }

        if(x+k>=25)
        {
            ll p=25-x;
            s[i]='z';
            k-=p;

        }
        else
        {
            s[i]=k+'a';
            k=0;
        }

    }

    if(k!=0)
    {
        printf("-1");
        return 0;
    }
   // printf("%s\n",s);
   cout<<s<<endl;
}


#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int N = 100100;

int main()
{
    int  n,k;
     char s[N];
    scanf("%d%d", &n, &k);
	scanf("%s", s);
	char t[N];
    for(int i=0;i<n;i++)
    {

        int x=int(s[i]-'a');
        int y=25-x;
        if(x>y)
        {
            int d=min(x,k);
           t[i]=char(s[i]-d);
           k-=d;

        }
        else
        {
            int d=min(y,k);
            t[i]=char(s[i]+d);
            k-=d;
        }
    }

  /*  if(k!=0)
    {
        printf("-1");
        return 0;
    }
//    puts(ans); */
t[n]=0;
puts(t);
 //  cout<<s<<endl;
}


#include "bits/stdc++.h"
using namespace std;
#define FOR(i,n) for(LL i=0; i<n; i++)
#define RFOR(i,n) for(LL i=n-1; i>=0; i--)
#define FILL(A,value) memset(A,value,sizeof(A))
#define LL long long int
#define sI(a) scanf("%d",&a)
#define pI(a) printf("%d",a)
#define sI2(a,b) sI(a),sI(b)
#define pI2(a,b) pI(a) , pI(b)
#define sL(a) scanf("%lld",&a)
#define pL(a) printf("%lld",a)
#define sL2(a,b) sL(a),sL(b)
#define pL2(a,b) pL(a) , pL(b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define pN printf("\n")
#define pS printf(" ");
#define PI 3.14159
#define pb push_back
#define mp make_pair
#define MOD 1000000007
inline int gcd(int a, int b){return (b == 0 ? a : gcd(b, a % b));}
inline int lcm(int a, int b){return (a * (b / gcd(a, b))); }
inline LL bigmod(LL a,LL b,LL m){if(b==0)return 1%m;LL x=bigmod(a,b/2,m);x=(x*x)%m;if(b%2==1){x=(x*a)%m;}return x;}
inline LL phi(LL n) {LL ret=n;for(LL i=2; i*i<=n; i++){if(n%i==0){while(n%i==0)n/=i;}ret-=ret/i;}if(n>1){ret-=ret/n;}return ret;}
LL missing_number(LL A[],LL n){LL x1=A[0],x2=1;for(int i=1; i<n; i++)x1^=A[i];for(int i=2; i<=n+1; i++)x2^=i;return (x1^x2);}
bool isFibo(LL n){LL A=(5*n*n+4);LL B=(5*n*n-4); LL C=sqrt(A); LL D=sqrt(B); return (A==(C*C)||B==(D*D));}
LL classini(LL n){return (n&1)? -1: 1;} // f(n-1)*f(n+1) - f(n)*f(n)
LL factorial(int n){return (n == 1 || n == 0) ? 1 : factorial(n - 1) * n;}
LL catanal(LL n) {return (factorial(2*n)/((factorial(n+1)*factorial(n))));}//Dyck path// //1,1,2,5,14,42,132,429,1430,4862,16796,58786, 208012, 742900, 2674440, 9694845, 35357670, 129644790, 477638700, 1767263190, 6564120420, 24466267020, 91482563640, 343059613650, 1289904147324, 4861946401452
string orientation_3_ordered_point(vector< pair<int,int> >V){LL value=(V[1].second-V[0].second)*(V[2].first-V[1].first)-(V[1].first*V[0].first)*(V[2].second-V[1].second);string res;if(value==0)res="colinear";value ==1 ? res="clockwise" : res="counterclockwise";return res;}
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};
int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};

string make_string(LL num){stringstream ss;ss<<num;string s;ss>>s;return s;}
LL make_num(string s){stringstream ss;LL tmp;ss<<s;ss>>tmp;return tmp;}

int SET(int mask,int pos){return (mask|(1<<pos));}
int check(int mask,int pos){return (mask&(1<<pos));}

void run(){
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
}

#define MX 100001

int main(int argc, char const *argv[])
{
    LL n,k;
    cin>>n>>k;
    string a,ans="";
    cin>>a;
    for(int i=0; i<n; i++){
        int value= (int)(a[i]-'a');
        char add;
        LL curmx=-1;
        for(int j=0; j<26; j++){
            if(abs(value-j)<=k && j>=curmx){
                curmx=abs(value-j);
                add=(char)('a'+j);
            }
        }
        ans+=add;
        k-=curmx;
    }
    if(k!=0){
        ans="-1";
    }
    cout<<ans<<endl;
    return 0;
}


#include "bits/stdc++.h"
using namespace std;
#define FOR(i,n) for(LL i=0; i<n; i++)
#define RFOR(i,n) for(LL i=n-1; i>=0; i--)
#define FILL(A,value) memset(A,value,sizeof(A))
#define LL long long int
#define sI(a) scanf("%d",&a)
#define pI(a) printf("%d",a)
#define sI2(a,b) sI(a),sI(b)
#define pI2(a,b) pI(a) , pI(b)
#define sL(a) scanf("%lld",&a)
#define pL(a) printf("%lld",a)
#define sL2(a,b) sL(a),sL(b)
#define pL2(a,b) pL(a) , pL(b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define pN printf("\n")
#define pS printf(" ");
#define PI 3.14159
#define pb push_back
#define mp make_pair
#define MOD 1000000007
inline int gcd(int a, int b){return (b == 0 ? a : gcd(b, a % b));}
inline int lcm(int a, int b){return (a * (b / gcd(a, b))); }
inline LL bigmod(LL a,LL b,LL m){if(b==0)return 1%m;LL x=bigmod(a,b/2,m);x=(x*x)%m;if(b%2==1){x=(x*a)%m;}return x;}
inline LL phi(LL n) {LL ret=n;for(LL i=2; i*i<=n; i++){if(n%i==0){while(n%i==0)n/=i;}ret-=ret/i;}if(n>1){ret-=ret/n;}return ret;}
LL missing_number(LL A[],LL n){LL x1=A[0],x2=1;for(int i=1; i<n; i++)x1^=A[i];for(int i=2; i<=n+1; i++)x2^=i;return (x1^x2);}
bool isFibo(LL n){LL A=(5*n*n+4);LL B=(5*n*n-4); LL C=sqrt(A); LL D=sqrt(B); return (A==(C*C)||B==(D*D));}
LL classini(LL n){return (n&1)? -1: 1;} // f(n-1)*f(n+1) - f(n)*f(n)
LL factorial(int n){return (n == 1 || n == 0) ? 1 : factorial(n - 1) * n;}
LL catanal(LL n) {return (factorial(2*n)/((factorial(n+1)*factorial(n))));}//Dyck path// //1,1,2,5,14,42,132,429,1430,4862,16796,58786, 208012, 742900, 2674440, 9694845, 35357670, 129644790, 477638700, 1767263190, 6564120420, 24466267020, 91482563640, 343059613650, 1289904147324, 4861946401452
string orientation_3_ordered_point(vector< pair<int,int> >V){LL value=(V[1].second-V[0].second)*(V[2].first-V[1].first)-(V[1].first*V[0].first)*(V[2].second-V[1].second);string res;if(value==0)res="colinear";value ==1 ? res="clockwise" : res="counterclockwise";return res;}
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};
int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};

string make_string(LL num){stringstream ss;ss<<num;string s;ss>>s;return s;}
LL make_num(string s){stringstream ss;LL tmp;ss<<s;ss>>tmp;return tmp;}

int SET(int mask,int pos){return (mask|(1<<pos));}
int check(int mask,int pos){return (mask&(1<<pos));}

void run(){
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
}

#define MX 100001

int main(){
    string s;
    long long int n,k;
    cin>>n>>k;
    cin>>s;
    long long int ans=0;

    for(int i=0;s[i];i++){
        long long int diff1=s[i]-'a';
        long long int diff2='z'-s[i];
        if(diff1>diff2) {s[i]=s[i]-min(diff1,k); k=k-min(diff1,k);}
        else {s[i]=s[i]+min(diff2,k); k=k-min(diff2,k);}
    }
    if(k!=0) cout<<-1;
    else cout<<s;
}


#include "bits/stdc++.h"
using namespace std;
#define FOR(i,n) for(LL i=0; i<n; i++)
#define RFOR(i,n) for(LL i=n-1; i>=0; i--)
#define FILL(A,value) memset(A,value,sizeof(A))
#define LL long long int
#define sI(a) scanf("%d",&a)
#define pI(a) printf("%d",a)
#define sI2(a,b) sI(a),sI(b)
#define pI2(a,b) pI(a) , pI(b)
#define sL(a) scanf("%lld",&a)
#define pL(a) printf("%lld",a)
#define sL2(a,b) sL(a),sL(b)
#define pL2(a,b) pL(a) , pL(b)
#define min3(a,b,c) min(a,min(b,c))
#define max3(a,b,c) max(a,max(b,c))
#define pN printf("\n")
#define pS printf(" ");
#define PI 3.14159
#define pb push_back
#define mp make_pair
#define MOD 1000000007
inline int gcd(int a, int b){return (b == 0 ? a : gcd(b, a % b));}
inline int lcm(int a, int b){return (a * (b / gcd(a, b))); }
inline LL bigmod(LL a,LL b,LL m){if(b==0)return 1%m;LL x=bigmod(a,b/2,m);x=(x*x)%m;if(b%2==1){x=(x*a)%m;}return x;}
inline LL phi(LL n) {LL ret=n;for(LL i=2; i*i<=n; i++){if(n%i==0){while(n%i==0)n/=i;}ret-=ret/i;}if(n>1){ret-=ret/n;}return ret;}
LL missing_number(LL A[],LL n){LL x1=A[0],x2=1;for(int i=1; i<n; i++)x1^=A[i];for(int i=2; i<=n+1; i++)x2^=i;return (x1^x2);}
bool isFibo(LL n){LL A=(5*n*n+4);LL B=(5*n*n-4); LL C=sqrt(A); LL D=sqrt(B); return (A==(C*C)||B==(D*D));}
LL classini(LL n){return (n&1)? -1: 1;} // f(n-1)*f(n+1) - f(n)*f(n)
LL factorial(int n){return (n == 1 || n == 0) ? 1 : factorial(n - 1) * n;}
LL catanal(LL n) {return (factorial(2*n)/((factorial(n+1)*factorial(n))));}//Dyck path// //1,1,2,5,14,42,132,429,1430,4862,16796,58786, 208012, 742900, 2674440, 9694845, 35357670, 129644790, 477638700, 1767263190, 6564120420, 24466267020, 91482563640, 343059613650, 1289904147324, 4861946401452
string orientation_3_ordered_point(vector< pair<int,int> >V){LL value=(V[1].second-V[0].second)*(V[2].first-V[1].first)-(V[1].first*V[0].first)*(V[2].second-V[1].second);string res;if(value==0)res="colinear";value ==1 ? res="clockwise" : res="counterclockwise";return res;}
int dx[]={1,-1,0,0};
int dy[]={0,0,1,-1};
int fx[]={+0,+0,+1,-1,-1,+1,-1,+1};
int fy[]={-1,+1,+0,+0,+1,+1,-1,-1};

string make_string(LL num){stringstream ss;ss<<num;string s;ss>>s;return s;}
LL make_num(string s){stringstream ss;LL tmp;ss<<s;ss>>tmp;return tmp;}

int SET(int mask,int pos){return (mask|(1<<pos));}
int check(int mask,int pos){return (mask&(1<<pos));}

void run(){
    freopen("in.txt","r",stdin);
    freopen("out.txt","w",stdout);
}

#define MX 100001

int main(int argc, char const *argv[])
{
    LL n,k;
    cin>>n>>k;
    string a,ans="";
    cin>>a;
    for(int i=0; i<n; i++){
        int value= (int)(a[i]-'a');
        char add;
        LL curmx=-1;
        for(int j=0; j<26; j++){
            if(abs(value-j)<=k && j>=curmx){
                curmx=abs(value-j);
                add=(char)('a'+j);
            }
        }
        ans+=add;
        k-=curmx;
    }
    if(k!=-1){
        ans=-1;
    }
    cout<<ans<<endl;
    return 0;
}


/*
░░░░██████████████████
░░▄███████▀▀▀▀▀▀███████▄
░▐████▀▒mohammad▒▀██████▄
░███▀▒▒▒▒alaa▒▒▒▒▒▒▀█████
░▐██▒▒▒alwrawrah▒▒▒▒▒████▌
░▐█▌▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒████▌
░░█▒▄▀▀▀▀▀▄▒▒▄▀▀▀▀▀▄▒▐███▌
░░░▐░░░▄▄░░▌▐░░░▄▄░░▌▐███▌
░▄▀▌░░░▀▀░░▌▐░░░▀▀░░▌▒▀▒█▌
░▌▒▀▄░░░░▄▀▒▒▀▄░░░▄▀▒▒▄▀▒▌
░▀▄▐▒▀▀▀▀▒▒▒▒▒▒▀▀▀▒▒▒▒▒▒█
░░░▀▌▒▄██▄▄▄▄████▄▒▒▒▒█▀
░░░░▄██████████████▒▒▐▌
░░░▀███▀▀████▀█████▀▒▌
░░░░░▌▒▒▒▄▒▒▒▄▒▒▒▒▒▒▐
░░░░░▌▒▒▒▒▀▀▀▒▒▒▒▒▒▒▐
*/

#include "iostream"
#include "vector"
#include "map"
#include "math.h"
#include "string"
#include "algorithm"
#include "set"
#include <string.h>
#include <queue>
#include <stack>

using namespace	std;

typedef long long ll ;

int a[100010] , n , k , ans[100010];
string s ;

int main(){
	cin >> n >> k ;
	cin >> s ;
	for(int i = 0 ; i < n ; ++i){
		a[i] = s[i] - 'a' + 1;
	}
	for(int i = 0 ; i < n ; ++i){
		int d = 26 - a[i];
		if(k == 0){
			ans[i] = a[i];
			continue ;
		}
		if(k > d){
			ans[i] = d + a[i];
			k -= d ;
		}else{
			ans[i] = a[i] + k ;
			k -= k ;
		}
	}
	string o ;
	for(int i = 0 ; i < n ; ++i){
		char z = 'a';
		int sa = 0 ;
		while(sa < ans[i] - 1){
			sa++;
			z++;
		}
		o += z ;
	}
	if(k)
		cout << -1 << endl;
	else
		cout << o << endl;
}


/*
░░░░██████████████████
░░▄███████▀▀▀▀▀▀███████▄
░▐████▀▒mohammad▒▀██████▄
░███▀▒▒▒▒alaa▒▒▒▒▒▒▀█████
░▐██▒▒▒alwrawrah▒▒▒▒▒████▌
░▐█▌▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒████▌
░░█▒▄▀▀▀▀▀▄▒▒▄▀▀▀▀▀▄▒▐███▌
░░░▐░░░▄▄░░▌▐░░░▄▄░░▌▐███▌
░▄▀▌░░░▀▀░░▌▐░░░▀▀░░▌▒▀▒█▌
░▌▒▀▄░░░░▄▀▒▒▀▄░░░▄▀▒▒▄▀▒▌
░▀▄▐▒▀▀▀▀▒▒▒▒▒▒▀▀▀▒▒▒▒▒▒█
░░░▀▌▒▄██▄▄▄▄████▄▒▒▒▒█▀
░░░░▄██████████████▒▒▐▌
░░░▀███▀▀████▀█████▀▒▌
░░░░░▌▒▒▒▄▒▒▒▄▒▒▒▒▒▒▐
░░░░░▌▒▒▒▒▀▀▀▒▒▒▒▒▒▒▐
*/

#include "iostream"
#include "vector"
#include "map"
#include "math.h"
#include "string"
#include "algorithm"
#include "set"
#include <string.h>
#include <queue>
#include <stack>

using namespace	std;

typedef long long ll ;

int a[100010] , n , k , ans[100010];
string s ;

int main(){

	cin >> n >> k ;
	cin >> s ;
	for(int i = 0 ; i < n ; ++i){
		a[i] = s[i] - 'a';
	}
	for(int i = 0 ; i < n ; ++i){
		int d = 26 - a[i];
		if(k == 0){
			ans[i] = a[i];
			continue ;
		}
		if(k > d){
			ans[i] = d;
			k -= d ;
		}else{
			ans[i] = a[i] + k ;
			k -= k ;
		}
	}
	string o ;
	for(int i = 0 ; i < n ; ++i){
		char z = 'a';
		int sa = 0 ;
		while(sa < ans[i]){
			sa++;
			z++;
		}
		o += z ;
	}
	if(k)
		cout << -1 << endl;
	else
		cout << o << endl;
}


/*
░░░░██████████████████
░░▄███████▀▀▀▀▀▀███████▄
░▐████▀▒mohammad▒▀██████▄
░███▀▒▒▒▒alaa▒▒▒▒▒▒▀█████
░▐██▒▒▒alwrawrah▒▒▒▒▒████▌
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*/

#include "iostream"
#include "vector"
#include "map"
#include "math.h"
#include "string"
#include "algorithm"
#include "set"
#include <string.h>
#include <queue>
#include <stack>

using namespace	std;

typedef long long ll ;

int a[100010] , n , k , ans[100010];
string s ;

int main(){
	cin >> n >> k ;
	cin >> s ;
	for(int i = 0 ; i < n ; ++i){
		a[i] = s[i] - 'a' + 1;
	}
	//cout << s << endl;
	for(int i = 0 ; i < n ; ++i){
		int d = 26 - a[i] , d1 = a[i] - 1;
		if(k == 0){
			ans[i] = a[i];
			continue ;
		}
		d = max(d , d1);
		if(k > d){
			if(d == d1)
				ans[i] = a[i] - d;
			else
				ans[i] = d + a[i];
			k -= d ;
		}else{
			if(d != d1)
				ans[i] = a[i] + k ;
			else
				ans[i] = a[i] - k ;
			k -= k ;
		}
	}
	//cout << k << endl;
	string o ;
	for(int i = 0 ; i < n ; ++i){
		char z = 'a';
		int sa = 0 ;
		while(sa < ans[i] - 1){
			sa++;
			z++;
		}
		o += z ;
	}
	if(k)
		cout << -1 << endl;
	else
		cout << o << endl;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    int l = n;
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    int num;
    for(int i = 0; i < n; i++)
    {
        int need = k/l;
        int con = a[i] - 'a';
        int num1 = con + need;
        int num2 = con - need;
        int extra = 0;
        if(num1 <= 25)
        {
            num = num1;
        }
        else if(num2 >= 0)
        {
            num = num2;
        }
        else
        {
            if(con - 0 > 25 - con)
            {
                num = 0;
                extra = need - (con - 0);
            }
            else
            {
                num = 25;
                extra = need - (25 - con);
            }
        }
        a[i] = num + 'a';
        k = k - need + extra;
        l--;
    }
    if(k  != 0)
    {
        printf("%d\n",-1);
        return 0;
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    int need = k / n;
    if(need > 25) {printf("%d\n",-1);return 0;}
    else
    {
        for(int i = 0; i < n; i++)
        {
            char ch;
            int val = ((a[i]-'a')+need);
            //cout << val << endl;
            if( val <= 25)
            {
                ch = val + 'a';
                a[i] = ch;
            }
            else
            {
                val = ((a[i]-'a') - need);
                ch = val + 'a';
                a[i] = ch;
            }
            k -= need;
            if(k == 0)
             break;
            need = k / n;
        }
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    int l = n;
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    int num;
    for(int i = 0; i < n; i++)
    {
        int con = a[i] - 'a';
        if(con - 0 > 25 - con)
        {
            if(con - 0 <= k)
            {
                num = 0;
                k = k - (con - 0);
            }
            else
            {
                if(con + k <=25)
                {
                    num = con + k;
                    k = 0;
                }
                else
                {
                    num = con - k;
                    k = 0;
                }
            }
        }
        else
        {
            if(25 - con <= k)
            {
                num = 25;
                k = k - (25 - con);
            }
            else
            {
                if(con + k <=25)
                {
                    num = con + k;
                    k = 0;
                }
                else
                {
                    num = con - k;
                    k = 0;
                }
            }
        }
        a[i] = num + 'a';
    }
    if(k  != 0)
    {
        printf("%d\n",-1);
        return 0;
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    int l = n;
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    int need = k / n;
    if(need > 25) {printf("%d\n",-1);return 0;}
    else
    {
        for(int i = 0; i < n; i++)
        {
            //cout << need << endl;
            char ch;
            int val = ((a[i]-'a')+need);
            //cout << val << endl;
            if( val <= 25)
            {
                ch = val + 'a';
                a[i] = ch;
            }
            else
            {
                val = ((a[i]-'a') - need);
                if(val < 0)
                {
                    need+=val;
                    val = 0;

                }
                ch = val + 'a';
                a[i] = ch;
            }
            k -= need;
            l--;
            if(k == 0)
             break;
            need = k / l;
        }
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    int l = n;
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    for(int i = 0; i < n; i++)
    {
        int need = k/l;

        int num = int(a[i] - 'a') + need;
        //cout << num << endl;
        if(num > 25)
        {
            num = int(a[i] - 'a') - need;
            if(num < 0)
            {
                printf("-1\n");
                return 0;
            }
        }
        a[i] = num + 'a';
        k -= need;
        l--;
    }
    if(k  != 0)
    {
        printf("%d\n",-1);
        return 0;
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>

using namespace std;

int main()
{
    int n,k;
    scanf("%d %d",&n,&k);
    int l = n;
    char ch;
    scanf("%c",&ch);
    char a[n+1];
    gets(a);
    int need = k / n;
    if(need > 25) {printf("%d\n",-1);return 0;}
    else
    {
        for(int i = 0; i < n; i++)
        {
            //cout << need << endl;
            char ch;
            int val = ((a[i]-'a')+need);
            //cout << val << endl;
            if( val <= 25)
            {
                ch = val + 'a';
                a[i] = ch;
            }
            else
            {
                val = ((a[i]-'a') - need);
                ch = val + 'a';
                a[i] = ch;
            }
            k -= need;
            l--;
            if(k == 0)
             break;
            need = k / l;
        }
    }
  puts(a);
  return 0;
}


#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define popb pop_back()
#define sz size()
#define y1 dfsdsfsdfsd
#define next fdsfsdfjkl
#define endl "\n"
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
double pi = acos(-1.0);
const int inf = 1e9+7;
const ll INF = 1e18+7;
//////////////////////////////////////////

int n,k;
char a[100100];

char b[100100];

vector< pair<char,int> > vi;
int main(){speed;
    cin>>n>>k;

    for(int i=0;i<n;i++) cin>>a[i];

    for(int i=0;i<n;i++)
    {
        vi.pb(mp(a[i],i));
    }
    sort(vi.begin(),vi.end());

    int sum = k;

    for(int i=0;i<vi.sz;i++)
    {
        char st = vi[i].fi;
        char fn = 'z';

        int x = fn - st;

        if(sum>=x)
        {
            sum -= x;
            vi[i].fi='z';
        }
        else
        {
            char neww = st + sum;

            if(neww>'z')
            {
                cout<<-1;
                return 0;
            }
            vi[i].fi = neww;
            break;
        }
    }
    if(sum>0)
    {
        cout<<-1;
        return 0;
    }
    for(int i=0;i<vi.sz;i++) b[vi[i].se] = vi[i].fi;

    for(int i=0;i<n;i++) cout<<b[i];
}


#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define popb pop_back()
#define sz size()
#define y1 dfsdsfsdfsd
#define next fdsfsdfjkl
#define endl "\n"
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
double pi = acos(-1.0);
const int inf = 1e9+7;
const ll INF = 1e18+7;
//////////////////////////////////////////

int n,k;
char a[100100];

char b[100100];

vector< pair<char,int> > vi;
int main(){speed;
    cin>>n>>k;

    for(int i=0;i<n;i++) cin>>a[i];

    for(int i=0;i<n;i++)
    {
        vi.pb(mp(a[i],i));
    }
    sort(vi.begin(),vi.end());

    int sum = k;

    for(int i=0;i<vi.sz;i++)
    {
        char st = vi[i].fi;
        char fn = 'z';

        int x = fn - st;

        if(sum>=x)
        {
            sum -= x;
            vi[i].fi='z';
        }
        else
        {
            char neww = st + sum;

            if(neww>'z')
            {
                sum -=(neww-'z');
                vi[i].fi='z';
            }
            else
            {
                sum=0;
                vi[i].fi=neww;
            }
        }
    }
    if(sum>0)
    {
        cout<<-1;
        return 0;
    }
    for(int i=0;i<vi.sz;i++) b[vi[i].se] = vi[i].fi;

    for(int i=0;i<n;i++) cout<<b[i];
}


#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define popb pop_back()
#define sz size()
#define y1 dfsdsfsdfsd
#define next fdsfsdfjkl
#define endl "\n"
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
double pi = acos(-1.0);
const int inf = 1e9+7;
const ll INF = 1e18+7;
//////////////////////////////////////////

int n,k;
char a[100100];

char b[100100];

vector< pair<char,int> > vi;
int main(){speed;
    cin>>n>>k;

    for(int i=0;i<n;i++) cin>>a[i];

    for(int i=0;i<n;i++)
    {
        vi.pb(mp(a[i],i));
    }
    sort(vi.begin(),vi.end());

    int sum = k;

    for(int i=0;i<vi.sz;i++)
    {
        char st = vi[i].fi;
        char fn = 'z';

        char fn2 = 'a';
        int x = fn - st;
        int y = st - fn2;

        if(x<y)
        {
            if(sum>=y)
            {
                sum -= y;
                vi[i].fi='a';
            }
            else
            {
                char neww = st - sum;

                if(neww<'a')
                {
                    sum -=abs(neww-'a');
                    vi[i].fi='a';
                }
                else
                {
                    sum=0;
                    vi[i].fi=neww;
                }
            }
        }
        else{
            if(sum>=x)
            {
                sum -= x;
                vi[i].fi='z';
            }
            else
            {
                char neww = st + sum;

                if(neww>'z')
                {
                    sum -=(neww-'z');
                    vi[i].fi='z';
                }
                else
                {
                    sum=0;
                    vi[i].fi=neww;
                }
            }
        }
    }
    if(sum>0)
    {
        cout<<-1;
        return 0;
    }
    for(int i=0;i<vi.sz;i++) b[vi[i].se] = vi[i].fi;

    for(int i=0;i<n;i++) cout<<b[i];
}


#include<bits/stdc++.h>
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define popb pop_back()
#define sz size()
#define y1 dfsdsfsdfsd
#define next fdsfsdfjkl
#define endl "\n"
#define speed ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
double pi = acos(-1.0);
const int inf = 1e9+7;
const ll INF = 1e18+7;
//////////////////////////////////////////

int n,k;
char a[100100];

char b[100100];

vector< pair<char,int> > vi;
int main(){speed;
    cin>>n>>k;

    for(int i=0;i<n;i++) cin>>a[i];

    for(int i=0;i<n;i++)
    {
        vi.pb(mp(a[i],i));
    }
    sort(vi.begin(),vi.end());

    int sum = k;

    for(int i=0;i<vi.sz;i++)
    {
        char st = vi[i].fi;
        char fn = 'z';

        int x = fn - st;

        if(sum>=x)
        {
            sum -= x;
            vi[i].fi='z';
        }
        else
        {
            char neww = st + sum;

            sum = 0;
            if(neww>'z')
            {
                cout<<-1;
                return 0;
            }
            vi[i].fi = neww;
            break;
        }
    }
    if(sum>0)
    {
        cout<<-1;
        return 0;
    }
    for(int i=0;i<vi.sz;i++) b[vi[i].se] = vi[i].fi;

    for(int i=0;i<n;i++) cout<<b[i];
}


			#include<bits/stdc++.h>
            #include<vector>
            #include<list>
            #include<string>
            #include<algorithm>
            #include <iomanip>
            #include<cstdlib>
             #include<set>

            using namespace std;
            #define ll long long
            //#define for(n) for(i=0;i<n;i++)
           #define pb push_back
          //#define mod 1000000007

    ll prime(ll n)
{
    // Corner cases
    if (n <= 1)
        return 0;
    if (n <= 3)
        return 1;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return 0;

    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return 0;

    return 1;
}

int main()
{
   ll n,k;
   string s;
   cin>>n>>k;
   cin>>s;

   ll i,j,t;
   string s1="";

   for(i=0;i<n;i++)
   {
      j=int(s[i])-96;

   	  if(k>=26)
   	  {
   	     if((j-1)>(26-j))
			{
			  s1.pb('a');
			  k=k-(j-1);
			}
			else
			{
				s1.pb('z');
				k=k-(26-j);
			}
	  }
	  else if(k>0  && k<26)
	  {
	  	 if(j>13)
	  	 {
	  	 	if((j-1)<=k)
	  	 	{
	  	 	    s1.pb('a');
				k=k-(j-1);
			}
			else
			{
				t=j-k+96;
				s1.pb(char(t));
				k=k-(j-k);
			}
		 }
		 else
		 {
		 	if((26-j)<=k)
		 	{
		 	   s1.pb('z');
				k=k-(26-j);
			}
			else
			{
				t=j+k+96;
				//cout<<"tirth";
				s1.pb(char(t));
				k=0;
			}
		 }
	  }
	  else if(k==0)
	  {
	  	s1.pb(s[i]);
	  }

   }

   if(k==0)
	  cout<<s1;
	  else
	  cout<<"-1"<<endl;
}


			#include<bits/stdc++.h>
            #include<vector>
            #include<list>
            #include<string>
            #include<algorithm>
            #include <iomanip>
            #include<cstdlib>
             #include<set>

            using namespace std;
            #define ll long long
            //#define for(n) for(i=0;i<n;i++)
           #define pb push_back
          //#define mod 1000000007

    ll prime(ll n)
{
    // Corner cases
    if (n <= 1)
        return 0;
    if (n <= 3)
        return 1;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return 0;

    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return 0;

    return 1;
}

int main()
{
   ll n,k;
   string s;
   cin>>n>>k;
   cin>>s;

   ll i,j,t;
   string s1="";

   for(i=0;i<n;i++)
   {
      j=int(s[i])-96;

   	  if(k>=26)
   	  {
   	     if((j-1)>(26-j))
			{
			  s1.pb('a');
			  k=k-(j-1);
			}
			else
			{
				s1.pb('z');
				k=k-(26-j);
			}
	  }
	  else if(k>0  && k<26)
	  {
	  	 if(j>13)
	  	 {
	  	 	if((j-1)<=k)
	  	 	{
	  	 	    s1.pb('a');
				k=k-(j-1);
			}
			else
			{
				t=j-k+96;
				s.pb(char(t));
				k=k-(j-k);
			}
		 }
		 else
		 {
		 	if((26-j)<=k)
		 	{
		 	   s1.pb('z');
				k=k-(26-j);
			}
			else
			{
				t=j+k+96;
				//cout<<"tirth";
				s1.pb(char(t));
				k=0;
			}
		 }
	  }
	  else if(k==0)
	  {
	  	s1.pb(s[i]);
	  }

   }

   if(k==0)
	  cout<<s1;
	  else
	  cout<<"-1"<<endl;
}


			#include<bits/stdc++.h>
            #include<vector>
            #include<list>
            #include<string>
            #include<algorithm>
            #include <iomanip>
            #include<cstdlib>
             #include<set>

            using namespace std;
            #define ll long long
            //#define for(n) for(i=0;i<n;i++)
           #define pb push_back
          //#define mod 1000000007

    ll prime(ll n)
{
    // Corner cases
    if (n <= 1)
        return 0;
    if (n <= 3)
        return 1;

    // This is checked so that we can skip
    // middle five numbers in below loop
    if (n % 2 == 0 || n % 3 == 0)
        return 0;

    for (int i = 5; i * i <= n; i = i + 6)
        if (n % i == 0 || n % (i + 2) == 0)
            return 0;

    return 1;
}

int main()
{
   ll n,k;
   string s;
   cin>>n>>k;
   cin>>s;

   ll i,j,t;
   string s1="";

   for(i=0;i<n;i++)
   {
      j=int(s[i])-96;

   	  if(k>=26)
   	  {
   	     if((j-1)>(26-j))
			{
			  s1.pb('a');
			  k=k-(j-1);
			}
			else
			{
				s1.pb('z');
				k=k-(26-j);
			}
	  }
	  else if(k>0  && k<26)
	  {
	  	 if(j>13)
	  	 {
	  	 	if((j-1)<=k)
	  	 	{
	  	 	    s1.pb('a');
				k=k-(j-1);
			}
			else
			{
				t=j-k+96;
				s1.pb(char(t));
				k=0;
			}
		 }
		 else
		 {
		 	if((26-j)<=k)
		 	{
		 	   s1.pb('z');
				k=k-(26-j);
			}
			else
			{
				t=j+k+96;
				//cout<<"tirth";
				s1.pb(char(t));
				k=0;
			}
		 }
	  }
	  else if(k==0)
	  {
	  	s1.pb(s[i]);
	  }

   }

   if(k==0)
	  cout<<s1;
	  else
	  cout<<"-1"<<endl;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s;
    cin>>n>>k;
    cin>>s;

    rep(i,0,n)
    {
        a[i]=abs(s[i]-'z');
           //cout<<a[i]<<" ";
    }
    int i=0,sum=0;
    while(sum<=k)
    {
        if(i==n)
        {
            if(k>0)
            {
             cout<<-1;
             //return 0;
             }
            break;
        }

        if(sum+a[i]>k)
        {
            //cout<<"1223";
        s1+=(char)(s[i]+(k-sum));
            i++;
            break;
        }
        else
        {
            s1+='z';
           // cout<<i<<endl;
            sum+=a[i];
            i++;
        }
    }
    rep(j,i,n)
    s1+=s[j];

    cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//
string s;
int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n,k;

    cin>>n>>k;
    cin>>s;
    int y=ceil((double)(k)/(double)(n));
    if(y>25 || k<n)
    {
        cout<<-1;
        return 0;
    }
    if(k%n==0)
    {
        rep(i,0,n)
        cout<<(char)((int)s[i]+y);
    }
    else
    {
        int e=k%((n-1)*y);
        //cout<<e<<" "<<y<<endl;
        rep(i,0,n-1)
        {

            cout<<(char)((int)s[i]+y);
        }
        cout<<(char)((int)s[n-1]+e);

    }

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s;
    cin>>n>>k;
    cin>>s;

    rep(i,0,n)
    {
        a[i]=abs(s[i]-'z');
           //cout<<a[i]<<" ";
    }
    int i=0,sum=0;
    while(sum<=k)
    {
        if(i==n)
        {
            if(k>0)
            {
             cout<<-1;
             return 0;
             }
            break;
        }

        if(sum+a[i]>k)
        {
            //cout<<"1223";
        s1+=(char)(s[i]+(k-sum));
            i++;
            break;
        }
        else
        {
            s1+='z';
           // cout<<i<<endl;
            sum+=a[i];
            i++;
        }
    }
    rep(j,i,n)
    s1+=s[j];

    cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s;
    cin>>n>>k;
    cin>>s;

    rep(i,0,n)
    {
        a[i]=abs(s[i]-'z');
           //cout<<a[i]<<" ";
    }
    int i=0,sum=0;
    while(sum<=k)
    {
        if(i==n)
        {
            if((k/n)>25)
            {
             cout<<-1;
             return 0;
             }
            break;
        }

        if(sum+a[i]>k)
        {
            //cout<<"1223";
        s1+=(char)(s[i]+(k-sum));
            i++;
            break;
        }
        else
        {
            s1+='z';
           // cout<<i<<endl;
            sum+=a[i];
            i++;
        }
    }
    rep(j,i,n)
    s1+=s[j];

    cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s,s1;
    cin>>n>>k;
    cin>>s;
        int i=0,sum=0,mul;
        for(;i<n;i++)
        {
            int f1='z'-s[i];
            int f2=s[i]-'a';

            if(f1>f2)
            {

                if(sum+f1>k)
                {
                    mul=1;
                    break;
                }

                sum+=f1;
               s1+='z';

            }
            else
            {
                if(sum+f2>k)
                {
                    mul=-1;
//                    j=i;
                    break;
                }
                sum+=f2;

                s1+='a';
               // cout<<s1<<endl;
            }

        }
        if(k-sum)
        {

            if(mul==1)
            {

                s1+=(char)(s[i]+(k-sum));
            }
            else
                s1+=(char)(s[i]-(k-sum));

            i++;

        }
        for(int k=i;k<n;k++)
        {
                s1+=s[k];
        }

            if(s1.length()>n)
                cout<<-1;
            else
          cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//
string s;
int main()
{
    ios_base::sync_with_stdio(0);cin.tie(0);
    int n,k;

    cin>>n>>k;
    cin>>s;
    int y=ceil((double)(k)/(double)(n));
    if(y>25 || k<n)
    {
        cout<<-1;
        return 0;
    }
    if(k%n==0)
    {
        rep(i,0,n)
        {

            if((s[i]+y)>122)
            {
               cout<<(char)(((s[i]+y)-122)+96);
                     continue;
                //cout<<(char)(((s[i]+y)-122)+96);
            }

            cout<<(char)((int)s[i]+y);
        }
    }
    else
    {
        int e=k%((n-1)*y);
        //cout<<e<<" "<<y<<endl;
        rep(i,0,n-1)
        {
            if((s[i]+y)>122)
            {

               cout<<(char)(((s[i]+y)-122)+96);
                     continue;
                                //cout<<(char)(((s[i]+y)-122)+96);
            }

            cout<<(char)((int)s[i]+y);
        }
        //cout<<(char)((int)s[n-1]+e);

            if((s[n-1]+e)>122)
            {

               cout<<(char)(((s[n-1]+y)-122)+96);
                     return 0;
            }

            cout<<(char)((int)s[n-1]+e);

    }

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s,s1;
    cin>>n>>k;
    cin>>s;
        int j=0,sum=0,mul;
        rep(i,0,n)
        {
            int f1='z'-s[i];
            int f2=s[i]-'a';
            if(f1>f2)
            {

                if(sum+f1>k)
                {
                    mul=1;
                    j=i;
                    break;
                }

                sum+=f1;
               s1+='z';
            }
            else
            {
                if(sum+f2>k)
                {
                    mul=-1;
                    j=i;
                    break;
                }
                sum+=f2;
                s1+='a';
            }

        }
        if(k-sum)
        {

            if(mul==1)
            {

                s1+=(char)(s[j]+(k-sum));
            }
            else
                s1+=(char)(s[j]-(k-sum));

            j++;

        }
        for(int k=j;k<n;k++)
        {
                s1+=s[k];
        }

            if(s1.length()>n)
                cout<<-1;
            else
          cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> pii;
#define MEM(a,b) memset(a,(b),sizeof(a))
#define pb(x) push_back(x)
#define mk make_pair
#define ff first
#define ss second
#define rep(i,a,b) for( int i=a;i<b;i++)
#define test int t;cin>>t;while(t--)
#define bitcnt(x)  __builtin_popcountll(x)
#define mod 1000000007
#define decsort [](int a,int b){return a>b;}
#define decsort1 [](pii a,pii b){return a.ff>b.ff;}
inline int in(){int32_t x ; scanf("%d",&x) ; return x ; }
inline long long lin(){long long x ; scanf("%lld",&x) ; return x ;}
inline int mul(int a,int b) {   ll x = a ; x *=(ll)b ; if (x >= mod )x %= mod ;    return x;  }
inline int add(int a,int b) {   return (a+b)>=mod ?a+b-mod:a+b  ;}
inline int sub(int a,int b) {  return (a-b)<0 ? mod-b+a: a-b ;  }
inline ll pow(ll a,ll b){ ll res=1; while(b>0) { if(b & 1) res=res*a; b=b >> 1; a=a*a;} return res; }
const int MAX=INT_MAX;
const int MIN=INT_MIN;
//ios_base::sync_with_stdio(0);cin.tie(0);
int a[200005];
string s1;
int main()
{

    int n,k;

    string s;
    cin>>n>>k;
    cin>>s;

    rep(i,0,n)
    {
        a[i]=abs(s[i]-'z');
           //cout<<a[i]<<" ";
    }
    int i=0,sum=0;
    while(sum<=k)
    {
        if(i==n-1)
        {
            if(k>0)
            {
             cout<<-1;
             return 0;}
            break;
        }

        if(sum+a[i]>k)
        {
            //cout<<"1223";
        s1+=(char)(s[i]+(k-sum));
            i++;
            break;
        }
        else
        {
            s1+='z';
            sum+=a[i];
            i++;
        }
    }
    rep(j,i,n)
    s1+=s[j];

    cout<<s1;

	return 0;
}


#include<bits/stdc++.h>
using namespace std;
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
    string s;
    int k,n;
    cin>>n>>k;
    cin>>s;
  int y=ceil((double)(k)/(double)(n));
    if(y>25 || k<n)
    {
        cout<<-1;
        return 0;
    }

        int sum=0;
        int i=0;
        while(1)
        {
            if(s[i]=='z')
            {
                cout<<'a';
                sum+=25;
                i++;
                //cout<<" "<<s[i]<<" "<<sum<<endl;
                continue;
            }
            if((abs(s[i]-'z')+sum)<=k)
            {
                cout<<'z';

                sum+=abs(s[i]-'z');
                //cout<<s[i]<<" "<<sum<<endl;
//
                i++;
               // cout<<sum<<endl;x
                continue;
            }
            else
            {
              cout<<(char)(s[i]+k-sum);
              i++;
              break;
            }
        }

       for(int j=i;j<n;j++)
        cout<<s[j];

    return 0;

}


#include<bits/stdc++.h>
using namespace std;
int main()
{
ios_base::sync_with_stdio(0);cin.tie(0);
    string s;
    int k,n;
    cin>>n>>k;
    cin>>s;
  int y=ceil((double)(k)/(double)(n));
    if(y>25 || k<n)
    {
        cout<<-1;
        return 0;
    }

        int sum=0;
        int i=0;
        while(i<n)
        {
            if(s[i]=='z')
            {
                cout<<'a';
                sum+=25;
                i++;
                //cout<<" "<<s[i]<<" "<<sum<<endl;
                continue;
            }
            if((abs(s[i]-'z')+sum)<=k)
            {
                cout<<'z';

                sum+=abs(s[i]-'z');
                //cout<<s[i]<<" "<<sum<<endl;
//
                i++;
               // cout<<sum<<endl;x
                continue;
            }
            else
            {
              cout<<(char)(s[i]+k-sum);
              i++;
              break;
            }
        }

       for(int j=i;j<n;j++)
        cout<<s[j];

    return 0;

}


#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define all(a) (a).begin(), (a).end()
#define ll long long
#define endl "\n"
#define DE cout << "------" << endl
#define mems(a, b) memset(a, b, sizeof a)
#define pii pair<int, int>
#define REP(i, n) for (int i = 0; i < (n); i++)
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int n, m;
string s;
int main() {
    ios::sync_with_stdio(false);
    while (cin >> n >> m) {
        cin >> s;
        int max0 = 0;
        for (int i = 0; i < n; i++) {
            max0 += max(fabs(26 + 'a' - s[i]), fabs(s[i] - '0'));
        }
        if (max0 < m) {
            printf("-1\n");
            continue;
        }
        // cout << s << endl;
        // cout << max0 << endl;
        for (int i = 0; i < n; i++) {
            // cout << s[i] << endl;
            int fr = s[i] - 'a';
            int la = 26 + 'a' - s[i];
            if (la > fr) {
                if (la < m) {
                    // cout << "a" << endl;
                    printf("z");
                    m -= la;
                } else {
                    // cout << (char) (s[i] - m) << endl;
                    printf("%c", s[i] + m);
                    m = 0;
                }
            } else {
                if (fr < m) {
                    // cout << 'z' << endl;
                    printf("a");
                    m -= fr;
                } else {
                    // cout << (s[i] - m) << endl;
                    printf("%c", s[i] - m);
                    m = 0;
                }
            }
        }
        printf("\n");
    }
    return 0;
}


#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define all(a) (a).begin(), (a).end()
#define ll long long
#define endl "\n"
#define DE cout << "------" << endl
#define mems(a, b) memset(a, b, sizeof a)
#define pii pair<int, int>
#define REP(i, n) for (int i = 0; i < (n); i++)
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int n, m;
string s;
int main() {
    ios::sync_with_stdio(false);
    while (cin >> n >> m) {
        cin >> s;
        int max0 = 0;
        for (int i = 0; i < n; i++) {
            max0 += max(fabs(26 + 'a' - s[i]), fabs(s[i] - '0'));
        }
        if (max0 < m) {
            printf("-1\n");
            continue;
        }
        // cout << s << endl;
        // cout << max0 << endl;
        for (int i = 0; i < n; i++) {
            // cout << s[i] << endl;
            int fr = s[i] - 'a';
            int la = 25 + 'a' - s[i];
            // cout << fr << " " << la << endl;
            // cout << m << endl;
            if (la > fr) {
                if (la < m) {
                    // cout << "a" << endl;
                    printf("z");
                    m -= la;
                } else {
                    // cout << (char) (s[i] - m) << endl;
                    printf("%c", s[i] + m);
                    m = 0;
                }
            } else {
                if (fr < m) {
                    // cout << 'z' << endl;
                    printf("a");
                    m -= fr;
                } else {
                    // cout << (s[i] - m) << endl;
                    printf("%c", s[i] - m);
                    m = 0;
                }
            }
        }
        printf("\n");
    }
    return 0;
}


#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define all(a) (a).begin(), (a).end()
#define ll long long
#define endl "\n"
#define DE cout << "------" << endl
#define mems(a, b) memset(a, b, sizeof a)
#define pii pair<int, int>
#define REP(i, n) for (int i = 0; i < (n); i++)
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int n, m;
string s;
int main() {
    ios::sync_with_stdio(false);
    while (cin >> n >> m) {
        cin >> s;
        int max0 = 0;
        for (int i = 0; i < n; i++) {
            max0 += max(fabs(25 + 'a' - s[i]), fabs(s[i] - 'a'));
        }
        if (max0 < m) {
            printf("-1\n");
            continue;
        }
        // cout << s << endl;
        // cout << max0 << endl;
        for (int i = 0; i < n; i++) {
            // cout << s[i] << endl;
            int fr = s[i] - 'a';
            int la = 25 + 'a' - s[i];
            // cout << fr << " " << la << endl;
            // cout << m << endl;
            if (la > fr) {
                if (la < m) {
                    // cout << "a" << endl;
                    printf("z");
                    m -= la;
                } else {
                    // cout << (char) (s[i] - m) << endl;
                    printf("%c", s[i] + m);
                    m = 0;
                }
            } else {
                if (fr < m) {
                    // cout << 'z' << endl;
                    printf("a");
                    m -= fr;
                } else {
                    // cout << (s[i] - m) << endl;
                    printf("%c", s[i] - m);
                    m = 0;
                }
            }
        }
        printf("\n");
    }
    return 0;
}


#include <algorithm>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <vector>
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#define all(a) (a).begin(), (a).end()
#define ll long long
#define endl "\n"
#define DE cout << "------" << endl
#define mems(a, b) memset(a, b, sizeof a)
#define pii pair<int, int>
#define REP(i, n) for (int i = 0; i < (n); i++)
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 0x3f3f3f3f;
int n, m;
string s;
int main() {
    ios::sync_with_stdio(false);
    while (cin >> n >> m) {
        cin >> s;
        int max0 = 0;
        for (int i = 0; i < n; i++) {
            max0 += max(fabs(25 + 'a' - s[i]), fabs(s[i] - '0'));
        }
        if (max0 < m) {
            printf("-1\n");
            continue;
        }
        // cout << s << endl;
        // cout << max0 << endl;
        for (int i = 0; i < n; i++) {
            // cout << s[i] << endl;
            int fr = s[i] - 'a';
            int la = 25 + 'a' - s[i];
            // cout << fr << " " << la << endl;
            // cout << m << endl;
            if (la > fr) {
                if (la < m) {
                    // cout << "a" << endl;
                    printf("z");
                    m -= la;
                } else {
                    // cout << (char) (s[i] - m) << endl;
                    printf("%c", s[i] + m);
                    m = 0;
                }
            } else {
                if (fr < m) {
                    // cout << 'z' << endl;
                    printf("a");
                    m -= fr;
                } else {
                    // cout << (s[i] - m) << endl;
                    printf("%c", s[i] - m);
                    m = 0;
                }
            }
        }
        printf("\n");
    }
    return 0;
}


#include<bits/stdc++.h>
#define mem(dp,a) memset(dp,a,sizeof(dp))
#define pb(x) push_back(x)
#define m_p(x,y) make_pair(x,y)
#define f(n) for(ll i=0;i<n;i++)
#define r(n) for(ll j=0;j<n;j++)
#define F first
#define S second
#define pi 3.14159265359
#define hs ios_base::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
typedef long long int ll;
typedef long double ld;
ll ESP=1e18;
ll INF=1e9+7;

int main()
{
 hs;
 ll n,dist;
 cin>>n>>dist;
 string str;
 cin>>str;
 if(dist>n*25)
    cout<<"-1"<<endl;
 else
 {
  ll q=dist/n;
  ll rem=dist%n;
  vector<ll>vec;
  f(n)
   vec.pb(q);
  f(rem)
   vec[i]++;
  string ans="";
  for(ll i=0;i<n;i++)
  {
   ans+=(char)((ll(str[i])+vec[i])%123);
  }
  cout<<ans<<endl;
 }
 return 0;

}


#include<bits/stdc++.h>
#define mem(dp,a) memset(dp,a,sizeof(dp))
#define pb(x) push_back(x)
#define m_p(x,y) make_pair(x,y)
#define f(n) for(ll i=0;i<n;i++)
#define r(n) for(ll j=0;j<n;j++)
#define F first
#define S second
#define pi 3.14159265359
#define hs ios_base::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
typedef long long int ll;
typedef long double ld;
ll ESP=1e18;
ll INF=1e9+7;

int main()
{
 hs;
 ll n,dist;
 cin>>n>>dist;
 string str;
 cin>>str;
 if(dist>n*25)
    cout<<"-1"<<endl;
 else
 {
  ll q=dist/n;
  ll rem=dist%n;
  vector<ll>vec;
  f(n)
   vec.pb(q);
  f(rem)
   vec[i]++;
  string ans="";
  for(ll i=0;i<n;i++)
  {
   ll pp=(ll(str[i])+vec[i]);
   if(pp<=122)
    ans+=(char)(pp);
   else
    ans+=(char)(pp%123+97);
   //cout<<ans<<endl;
  }

  cout<<ans<<endl;
 }
 return 0;

}


#include<bits/stdc++.h>
#define mem(dp,a) memset(dp,a,sizeof(dp))
#define pb(x) push_back(x)
#define m_p(x,y) make_pair(x,y)
#define f(n) for(ll i=0;i<n;i++)
#define r(n) for(ll j=0;j<n;j++)
#define F first
#define S second
#define pi 3.14159265359
#define hs ios_base::sync_with_stdio(false);cin.tie(NULL);
using namespace std;
typedef long long int ll;
typedef long double ld;
ll ESP=1e18;
ll INF=1e9+7;

int main()
{
 hs;
 ll n,k;
 cin>>n>>k;
 string str;
 cin>>str;

 for(ll i=0;i<n&&k>0;i++)
 {
  ll xx=min(k,max((ll)(str[i]-'a'),(ll)('z'-str[i])));
  str[i]+=(str[i]+xx>'z')?-xx:xx;
  k-=xx;
 }
 if(k==0)
    cout<<str<<"\n";
 else
    cout<<"-1"<<"\n";
 return 0;

}


import java.io.IOException;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.util.Scanner;

public class Edu_1 {
	public static void main(String[] args){
		FasterScanner in=new FasterScanner();
		PrintWriter out=new PrintWriter(System.out);
		int n=in.nextInt();
		int k=in.nextInt();
		String s=in.nextLine();
		char[] a=new char[n];
		for(int i=0;i<n;i++){
			a[i]=(char)(s.charAt(i)-'a');
		}
		char[] ans=new char[n];
		int i=0;
		for(i=0;i<n;i++){
			int max=0;
			if(a[i]>=25-a[i]){
				max=a[i];
				if(k>=max){
					ans[i]='a';
					k-=max;
				}
				else if(k==0){
					ans[i]=(char)(a[i]+'a');
				}
				else{
					int c=a[i]-k>=0?a[i]-k:-1;
					if(c==-1){
						c=a[i]+k;
					}
					ans[i]=(char)(c+'a');
					k-=k;
				}
			}
			else{
				max=25-a[i];
				if(k>=max){
					ans[i]='z';
					k-=max;
				}
				else if(k==0){
					ans[i]=(char)(a[i]+'a');
				}
				else{
					int c=a[i]-k>=0?a[i]-k:-1;
					if(c==-1){
						c=a[i]+k;
					}
					ans[i]=(char)(c+'a');
					k-=k;
				}
			}
		}
		if(k>0){
			out.println(-1);
		}
		else{
			String j=new String(ans);
			out.println(j);
		}
		out.close();
	}

	static class FasterScanner {

	    private byte[] buf = new byte[1024];
	    private int curChar;
	    private int numChars;

	    public int read() {
	        if (numChars == -1) {
	            throw new InputMismatchException();
	        }
	        if (curChar >= numChars) {
	            curChar = 0;
	            try {
	                numChars = System.in.read(buf);
	            } catch (IOException e) {
	                throw new InputMismatchException();
	            }
	            if (numChars <= 0) {
	                return -1;
	            }
	        }
	        return buf[curChar++];
	    }

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

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

	    public long nextLong() {
	        int c = read();
	        while (isSpaceChar(c)) {
	            c = read();
	        }
	        int sgn = 1;
	        if (c == '-') {
	            sgn = -1;
	            c = read();
	        }
	        long res = 0;
	        do {
	            if (c < '0' || c > '9') {
	                throw new InputMismatchException();
	            }
	            res *= 10;
	            res += c - '0';
	            c = read();
	        } while (!isSpaceChar(c));
	        return res * sgn;
	    }

	    public int nextInt() {
	        int c = read();
	        while (isSpaceChar(c)) {
	            c = read();
	        }
	        int sgn = 1;
	        if (c == '-') {
	            sgn = -1;
	            c = read();
	        }
	        int res = 0;
	        do {
	            if (c < '0' || c > '9') {
	                throw new InputMismatchException();
	            }
	            res *= 10;
	            res += c - '0';
	            c = read();
	        } while (!isSpaceChar(c));
	        return res * sgn;
	    }

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

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

	    private boolean isSpaceChar(int c) {
	        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	    }

	    private boolean isEndOfLine(int c) {
	        return c == '\n' || c == '\r' || c == -1;
	    }
	}

}