def main():
    n,a,b = map(int,input().split())
    mod = 10**9+7
    s = pow(2,n,mod)
    nCa,nCb = 1,1
    for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

    for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

    for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

    for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
    print((s-nCa-nCb-1)%mod)


if __name__ == "__main__":
    main() def main():
    n,a,b = map(int,input().split())
    mod = 10**9+7
    s = pow(2,n,mod)
    nCa,nCb = 1,1
    for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

    for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

    for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

    for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
    print((s-nCa-nCb-1)%mod) main 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 s = pow(2,n,mod) s pow(2,n,mod) pow 2 n mod nCa,nCb = 1,1 nCa 1 nCb 1 for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

     i range(n-a+1, n+1) range n-a+1 n-a n a 1 n+1 n 1 nCa *= i nCa i nCa %= mod nCa mod for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

     i range(1,a+1) range 1 a+1 a 1 nCa *= pow(i,mod-2,mod) nCa pow(i,mod-2,mod) pow i mod-2 mod 2 mod nCa %= mod nCa mod for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

     i range(n-b+1, n+1) range n-b+1 n-b n b 1 n+1 n 1 nCb *= i nCb i nCb %= mod nCb mod for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
     i range(1,b+1) range 1 b+1 b 1 nCb *= pow(i,mod-2,mod) nCb pow(i,mod-2,mod) pow i mod-2 mod 2 mod nCb %= mod nCb mod print((s-nCa-nCb-1)%mod) print (s-nCa-nCb-1)%mod s-nCa-nCb-1 s-nCa-nCb s-nCa s nCa nCb 1 mod if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    n,a,b = map(int,input().split())
    mod = 10**9+7
    s = pow(2,n,mod)
    nCa,nCb = 1,1
    for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

    for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

    for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

    for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
    print((s-nCa-nCb-1)%mod) def main():
    n,a,b = map(int,input().split())
    mod = 10**9+7
    s = pow(2,n,mod)
    nCa,nCb = 1,1
    for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

    for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

    for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

    for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
    print((s-nCa-nCb-1)%mod) main
def main():
    n,a,b = map(int,input().split())
    mod = 10**9+7
    s = pow(2,n,mod)
    nCa,nCb = 1,1
    for i in range(n-a+1, n+1):
        nCa *= i
        nCa %= mod

    for i in range(1,a+1):
        nCa *= pow(i,mod-2,mod)
        nCa %= mod

    for i in range(n-b+1, n+1):
        nCb *= i
        nCb %= mod

    for i in range(1,b+1):
        nCb *= pow(i,mod-2,mod)
        nCb %= mod
    print((s-nCa-nCb-1)%mod)


if __name__ == "__main__":
    main()
