import sys

sys.setrecursionlimit(10 ** 7)
f_inf = float('inf')
mod = 10 ** 9 + 7


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

    def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

    total = pow(2, n, mod) - 1
    res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod)
    print(res % mod)


if __name__ == '__main__':
    resolve() import sys sys sys.setrecursionlimit(10 ** 7) sys.setrecursionlimit sys setrecursionlimit 10 ** 7 10 7 f_inf = float('inf') f_inf float('inf') float 'inf' mod = 10 ** 9 + 7 mod 10 ** 9 + 7 10 ** 9 10 9 7 def resolve():
    n, a, b = map(int, input().split())

    def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

    total = pow(2, n, mod) - 1
    res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod)
    print(res % mod) resolve n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

     cmb_mod x, y = 1, 1 x 1 y 1 for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
         i range(r) range r x = (x * (n - i)) % mod x (x * (n - i)) % mod x * (n - i) x n - i n i mod y = (y * (i + 1)) % mod y (y * (i + 1)) % mod y * (i + 1) y i + 1 i 1 mod return (x * pow(y, mod - 2, mod)) % mod (x * pow(y, mod - 2, mod)) % mod x * pow(y, mod - 2, mod) x pow(y, mod - 2, mod) pow y mod - 2 mod 2 mod mod n n r r mod mod total = pow(2, n, mod) - 1 total pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod) res total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod) total - cmb_mod(n, a, mod) total cmb_mod(n, a, mod) cmb_mod n a mod cmb_mod(n, b, mod) cmb_mod n b mod print(res % mod) print res % mod res mod if __name__ == '__main__':
    resolve() __name__ == '__main__' __name__ '__main__' resolve() resolve mod = 10 ** 9 + 7 10 ** 9 + 7 mod f_inf = float('inf') float('inf') f_inf def resolve():
    n, a, b = map(int, input().split())

    def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

    total = pow(2, n, mod) - 1
    res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod)
    print(res % mod) def resolve():
    n, a, b = map(int, input().split())

    def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

    total = pow(2, n, mod) - 1
    res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod)
    print(res % mod) resolve
import sys

sys.setrecursionlimit(10 ** 7)
f_inf = float('inf')
mod = 10 ** 9 + 7


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

    def cmb_mod(n, r, mod):
        x, y = 1, 1
        for i in range(r):
            x = (x * (n - i)) % mod
            y = (y * (i + 1)) % mod
        return (x * pow(y, mod - 2, mod)) % mod

    total = pow(2, n, mod) - 1
    res = total - cmb_mod(n, a, mod) - cmb_mod(n, b, mod)
    print(res % mod)


if __name__ == '__main__':
    resolve()
