from functools import reduce
n, a, b = map(int, input().split())
mod = 10**9 + 7

def f(A):
    bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1))
    bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1))
    return bunsi * pow(bunbo, mod-2, mod) % mod

ans = pow(2, n, mod) - f(a) -f(b) - 1
ans %= mod
print(ans) from functools import reduce 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 def f(A):
    bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1))
    bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1))
    return bunsi * pow(bunbo, mod-2, mod) % mod f bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1)) bunsi reduce(lambda x, y: x*y%mod, range(n, n-A, -1)) reduce lambda x, y: x*y%mod x*y%mod x*y x y mod x y range(n, n-A, -1) range n n-A n A -1 bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1)) bunbo reduce(lambda x, y: x*y%mod, range(1, A+1)) reduce lambda x, y: x*y%mod x*y%mod x*y x y mod x y range(1, A+1) range 1 A+1 A 1 return bunsi * pow(bunbo, mod-2, mod) % mod bunsi * pow(bunbo, mod-2, mod) % mod bunsi * pow(bunbo, mod-2, mod) bunsi pow(bunbo, mod-2, mod) pow bunbo mod-2 mod 2 mod mod A A ans = pow(2, n, mod) - f(a) -f(b) - 1 ans pow(2, n, mod) - f(a) -f(b) - 1 pow(2, n, mod) - f(a) -f(b) pow(2, n, mod) - f(a) pow(2, n, mod) pow 2 n mod f(a) f a f(b) f b 1 ans %= mod ans mod print(ans) print ans a, b = map(int, input().split()) map(int, input().split()) a mod = 10**9 + 7 10**9 + 7 mod ans = pow(2, n, mod) - f(a) -f(b) - 1 pow(2, n, mod) - f(a) -f(b) - 1 ans ans %= mod mod ans def f(A):
    bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1))
    bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1))
    return bunsi * pow(bunbo, mod-2, mod) % mod def f(A):
    bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1))
    bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1))
    return bunsi * pow(bunbo, mod-2, mod) % mod f b = map(int, input().split()) map(int, input().split()) b n, a, b = map(int, input().split()) map(int, input().split()) n
from functools import reduce
n, a, b = map(int, input().split())
mod = 10**9 + 7

def f(A):
    bunsi = reduce(lambda x, y: x*y%mod, range(n, n-A, -1))
    bunbo = reduce(lambda x, y: x*y%mod, range(1, A+1))
    return bunsi * pow(bunbo, mod-2, mod) % mod

ans = pow(2, n, mod) - f(a) -f(b) - 1
ans %= mod
print(ans)