import sys
input = sys.stdin.readline

def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    N,a,b=MI()
    M=2*(10**5) + 5
    def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
    ans=pow(2,N,mod)-1
    ans-=cmb(N,a)
    ans-=cmb(N,b)
    
    print(ans%mod)

main() import sys sys input = sys.stdin.readline input sys.stdin.readline sys.stdin sys stdin readline def I(): return int(input()) I def MI(): return map(int, input().split()) MI def LI(): return list(map(int, input().split())) LI def main():
    mod=10**9+7
    N,a,b=MI()
    M=2*(10**5) + 5
    def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
    ans=pow(2,N,mod)-1
    ans-=cmb(N,a)
    ans-=cmb(N,b)
    
    print(ans%mod) main mod=10**9+7 mod 10**9+7 10**9 10 9 7 N,a,b=MI() N MI() MI a b M=2*(10**5) + 5 M 2*(10**5) + 5 2*(10**5) 2 10**5 10 5 5 def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
     cmb if n - r < r: r = n - r
         n - r < r n - r n r r if r == 0: return 1
         r == 0 r 0 if r == 1: return n

         r == 1 r 1 n - r + k + 1 for k in range(r) for k in range(r) k range(r) range r for k in range(r) n - r + k + 1 n - r + k n - r n r k 1 numerator = [n - r + k + 1 for k in range(r)] numerator [n - r + k + 1 for k in range(r)] k + 1 for k in range(r) for k in range(r) k range(r) range r for k in range(r) k + 1 k 1 denominator = [k + 1 for k in range(r)] denominator [k + 1 for k in range(r)] for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

         p range(2,r+1) range 2 r+1 r 1 pivot = denominator[p - 1] pivot denominator[p - 1] denominator p - 1 p 1 if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

         pivot > 1 pivot 1 offset = (n - r) % p offset (n - r) % p n - r n r p for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

         k range(p-1,r,p) range p-1 p 1 r p numerator[k - offset] /= pivot numerator[k - offset] numerator k - offset k offset pivot denominator[k] /= pivot denominator[k] denominator k pivot result = 1 result 1 for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

         k range(r) range r if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

         numerator[k] > 1 numerator[k] numerator k 1 result *= int(numerator[k]) result int(numerator[k]) int numerator[k] numerator k result%=mod result mod return result result n n r r ans=pow(2,N,mod)-1 ans pow(2,N,mod)-1 pow(2,N,mod) pow 2 N mod 1 ans-=cmb(N,a) ans cmb(N,a) cmb N a ans-=cmb(N,b) ans cmb(N,b) cmb N b print(ans%mod) print ans%mod ans mod main() main def MI(): return map(int, input().split()) def MI(): return map(int, input().split()) MI def LI(): return list(map(int, input().split())) def LI(): return list(map(int, input().split())) LI input = sys.stdin.readline sys.stdin.readline input def main():
    mod=10**9+7
    N,a,b=MI()
    M=2*(10**5) + 5
    def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
    ans=pow(2,N,mod)-1
    ans-=cmb(N,a)
    ans-=cmb(N,b)
    
    print(ans%mod) def main():
    mod=10**9+7
    N,a,b=MI()
    M=2*(10**5) + 5
    def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
    ans=pow(2,N,mod)-1
    ans-=cmb(N,a)
    ans-=cmb(N,b)
    
    print(ans%mod) main def I(): return int(input()) def I(): return int(input()) I
import sys
input = sys.stdin.readline

def I(): return int(input())
def MI(): return map(int, input().split())
def LI(): return list(map(int, input().split()))

def main():
    mod=10**9+7
    N,a,b=MI()
    M=2*(10**5) + 5
    def cmb(n, r):
        if n - r < r: r = n - r
        if r == 0: return 1
        if r == 1: return n

        numerator = [n - r + k + 1 for k in range(r)]
        denominator = [k + 1 for k in range(r)]

        for p in range(2,r+1):
            pivot = denominator[p - 1]
            if pivot > 1:
                offset = (n - r) % p
                for k in range(p-1,r,p):
                    numerator[k - offset] /= pivot
                    denominator[k] /= pivot

        result = 1
        for k in range(r):
            if numerator[k] > 1:
                result *= int(numerator[k])
                result%=mod

        return result
        
    ans=pow(2,N,mod)-1
    ans-=cmb(N,a)
    ans-=cmb(N,b)
    
    print(ans%mod)

main()
