import numpy as np

mod = (10**9)+7

def modpow(x, n):

  ans = 1

  mod = (10**9)+7

  while(n > 0):

    if(bin(n & 1) == bin(1)):

      ans = ans*x

      ans %= mod

    x = x*x

    x %= mod

    n = n >> 1 #ビットシフト

  return ans





def nCr(n,r):

    mod = (10**9)+7

    r = min(n,r)

    bunsi = bunbo = 1

    for i in range(1,r+1):

      bunsi = (bunsi * (n+1-i) )% mod

      bunbo = bunbo * i % mod

    ans = (bunsi * pow(bunbo,mod-2,mod)) % mod

    return ans



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

print(((modpow(2,n)- 1 - nCr(n,a) - nCr(n,b) )% mod))

mod = (10**9)+7

def modpow(x, n):

  ans = 1

  mod = (10**9)+7

  while(n > 0):

    if(bin(n & 1) == bin(1)):

      ans = ans*x

      ans %= mod

    x = x*x

    x %= mod

    n = n >> 1 #ビットシフト

  return ans





def nCr(n,r):

    mod = (10**9)+7

    r = min(n,r)

    bunsi = bunbo = 1

    for i in range(1,r+1):

      bunsi = (bunsi * (n+1-i) )% mod

      bunbo = bunbo * i % mod

    ans = (bunsi * pow(bunbo,mod-2,mod)) % mod

    return ans



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

print(((modpow(2,n)- 1 - nCr(n,a) - nCr(n,b) )% mod))

import numpy as np

mod = (10**9) + 7


def modpow(x, n):
    ans = 1
    mod = (10**9) + 7
    while n > 0:
        if bin(n & 1) == bin(1):
            ans = ans * x
            ans %= mod
        x = x * x
        x %= mod
        n = n >> 1  # ビットシフト
    return ans


def nCr(n, r):
    mod = (10**9) + 7
    r = min(n, r)
    bunsi = bunbo = 1
    for i in range(1, r + 1):
        bunsi = (bunsi * (n + 1 - i)) % mod
        bunbo = bunbo * i % mod
    ans = (bunsi * pow(bunbo, mod - 2, mod)) % mod
    return ans


n, a, b = list(map(int, input().split()))
print(((modpow(2, n) - 1 - nCr(n, a) - nCr(n, b)) % mod))

mod = (10**9) + 7


def modpow(x, n):
    ans = 1
    mod = (10**9) + 7
    while n > 0:
        if bin(n & 1) == bin(1):
            ans = ans * x
            ans %= mod
        x = x * x
        x %= mod
        n = n >> 1  # ビットシフト
    return ans


def nCr(n, r):
    mod = (10**9) + 7
    r = min(n, r)
    bunsi = bunbo = 1
    for i in range(1, r + 1):
        bunsi = (bunsi * (n + 1 - i)) % mod
        bunbo = bunbo * i % mod
    ans = (bunsi * pow(bunbo, mod - 2, mod)) % mod
    return ans


n, a, b = list(map(int, input().split()))
print(((modpow(2, n) - 1 - nCr(n, a) - nCr(n, b)) % mod))

-import numpy as np -