def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk
n,a,b=map(int,input().split())
mod=10**9+7
ans=(2**n-1)%mod
aa=comb(n,a)%mod
bb=comb(n,b)%mod
ans-=aa+bb
print(ans%mod) def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk comb nCk = 1 nCk 1 MOD = 10**9+7 MOD 10**9+7 10**9 10 9 7 for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

     i range(n-k+1, n+1) range n-k+1 n-k n k 1 n+1 n 1 nCk *= i nCk i nCk %= MOD nCk MOD for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
     i range(1,k+1) range 1 k+1 k 1 nCk *= pow(i,MOD-2,MOD) nCk pow(i,MOD-2,MOD) pow i MOD-2 MOD 2 MOD nCk %= MOD nCk MOD return nCk nCk n n k k n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b mod=10**9+7 mod 10**9+7 10**9 10 9 7 ans=(2**n-1)%mod ans (2**n-1)%mod 2**n-1 2**n 2 n 1 mod aa=comb(n,a)%mod aa comb(n,a)%mod comb(n,a) comb n a mod bb=comb(n,b)%mod bb comb(n,b)%mod comb(n,b) comb n b mod ans-=aa+bb ans aa+bb aa bb print(ans%mod) print ans%mod ans mod a,b=map(int,input().split()) map(int,input().split()) a n,a,b=map(int,input().split()) map(int,input().split()) n ans-=aa+bb aa+bb ans b=map(int,input().split()) map(int,input().split()) b mod=10**9+7 10**9+7 mod def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk comb ans=(2**n-1)%mod (2**n-1)%mod ans bb=comb(n,b)%mod comb(n,b)%mod bb aa=comb(n,a)%mod comb(n,a)%mod aa
def comb(n,k):
    nCk = 1
    MOD = 10**9+7

    for i in range(n-k+1, n+1):
        nCk *= i
        nCk %= MOD

    for i in range(1,k+1):
        nCk *= pow(i,MOD-2,MOD)
        nCk %= MOD
    return nCk
n,a,b=map(int,input().split())
mod=10**9+7
ans=(2**n-1)%mod
aa=comb(n,a)%mod
bb=comb(n,b)%mod
ans-=aa+bb
print(ans%mod)