from functools import reduce



def comb(n, k, p):

  a = reduce(lambda x,y: x*y%p, list(range(n,n-k,-1)))

  b = reduce(lambda x,y: x*y%p, list(range(1,k+1)))

  return (a*pow(b, p-2, p))%p

      

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

MOD = 10**9 + 7

     

print(((pow(2,n,MOD) - 1 - comb(n, a, MOD) - comb(n, b, MOD))%MOD))
from functools import reduce

  

def perm(n, k, p):

  ret = 1

  for i in range(n, n-k, -1):

    ret = (ret * i)%p

  return ret



def comb(n, k, p):

  """power_funcを用いて(nCk) mod p を求める"""

  a = perm(n, k, p)

  b = perm(k, k, p)

  return (a*pow(b, p-2, p))%p

  

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



MOD = 10**9 + 7





print(((pow(2,n,MOD) - 1 - comb(n, a, MOD) - comb(n, b, MOD))%MOD))
from functools import reduce


def comb(n, k, p):
    a = reduce(lambda x, y: x * y % p, list(range(n, n - k, -1)))
    b = reduce(lambda x, y: x * y % p, list(range(1, k + 1)))
    return (a * pow(b, p - 2, p)) % p


n, a, b = list(map(int, input().split()))
MOD = 10**9 + 7
print(((pow(2, n, MOD) - 1 - comb(n, a, MOD) - comb(n, b, MOD)) % MOD))

from functools import reduce


def perm(n, k, p):
    ret = 1
    for i in range(n, n - k, -1):
        ret = (ret * i) % p
    return ret


def comb(n, k, p):
    """power_funcを用いて(nCk) mod p を求める"""
    a = perm(n, k, p)
    b = perm(k, k, p)
    return (a * pow(b, p - 2, p)) % p


n, a, b = list(map(int, input().split()))
MOD = 10**9 + 7
print(((pow(2, n, MOD) - 1 - comb(n, a, MOD) - comb(n, b, MOD)) % MOD))

+def perm(n, k, p): +    ret = 1 +    for i in range(n, n - k, -1): +        ret = (ret * i) % p +    return ret + + -    a = reduce(lambda x, y: x * y % p, list(range(n, n - k, -1))) -    b = reduce(lambda x, y: x * y % p, list(range(1, k + 1))) +    """power_funcを用いて(nCk) mod p を求める""" +    a = perm(n, k, p) +    b = perm(k, k, p)