n,a,b=map(int,input().split())
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

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)



 n,a,b=map(int,input().split()) n map(int,input().split()) map int input().split() ().split () input split a b 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 x=pow(2,n,10**9+7)-1 x pow(2,n,10**9+7)-1 pow(2,n,10**9+7) pow 2 n 10**9+7 10**9 10 9 7 1 y=comb(n,a)+comb(n,b) y comb(n,a)+comb(n,b) comb(n,a) comb n a comb(n,b) comb n b ans=x-y ans x-y x y while ans<0:
          ans+=10**9+7 ans<0 ans 0 ans+=10**9+7 ans 10**9+7 10**9 10 9 7 print(ans) print ans b=map(int,input().split()) map(int,input().split()) b n,a,b=map(int,input().split()) map(int,input().split()) n ans+=10**9+7 10**9+7 ans y=comb(n,a)+comb(n,b) comb(n,a)+comb(n,b) y ans=x-y x-y ans 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 a,b=map(int,input().split()) map(int,input().split()) a x=pow(2,n,10**9+7)-1 pow(2,n,10**9+7)-1 x
n,a,b=map(int,input().split())
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

x=pow(2,n,10**9+7)-1
y=comb(n,a)+comb(n,b)
ans=x-y





while ans<0:
          ans+=10**9+7
print(ans)




