#!/usr/bin/env python3
from functools import reduce

mod = 10**9 + 7


def cmb(n, r, m):
    def mul(a, b):
        return a * b % m

    r = min(n - r, r)
    if r == 0:
        return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1, r + 1))
    return over * pow(under, m - 2, m)


n, a, b = map(int, input().split())
print((pow(2, n, mod) - 1 - cmb(n, a, mod) - cmb(n, b, mod)) % mod) from functools import reduce mod = 10**9 + 7 mod 10**9 + 7 10**9 10 9 7 def cmb(n, r, m):
    def mul(a, b):
        return a * b % m

    r = min(n - r, r)
    if r == 0:
        return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1, r + 1))
    return over * pow(under, m - 2, m) cmb def mul(a, b):
        return a * b % m

     mul return a * b % m a * b % m a * b a b m a a b b r = min(n - r, r) r min(n - r, r) min n - r n r r if r == 0:
        return 1
     r == 0 r 0 return 1 1 over = reduce(mul, range(n, n - r, -1)) over reduce(mul, range(n, n - r, -1)) reduce mul range(n, n - r, -1) range n n - r n r -1 under = reduce(mul, range(1, r + 1)) under reduce(mul, range(1, r + 1)) reduce mul range(1, r + 1) range 1 r + 1 r 1 return over * pow(under, m - 2, m) over * pow(under, m - 2, m) over pow(under, m - 2, m) pow under m - 2 m 2 m n n r r m m n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b print((pow(2, n, mod) - 1 - cmb(n, a, mod) - cmb(n, b, mod)) % mod) print (pow(2, n, mod) - 1 - cmb(n, a, mod) - cmb(n, b, mod)) % mod pow(2, n, mod) - 1 - cmb(n, a, mod) - cmb(n, b, mod) pow(2, n, mod) - 1 - cmb(n, a, mod) pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 cmb(n, a, mod) cmb n a mod cmb(n, b, mod) cmb n b mod mod mod = 10**9 + 7 10**9 + 7 mod def cmb(n, r, m):
    def mul(a, b):
        return a * b % m

    r = min(n - r, r)
    if r == 0:
        return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1, r + 1))
    return over * pow(under, m - 2, m) def cmb(n, r, m):
    def mul(a, b):
        return a * b % m

    r = min(n - r, r)
    if r == 0:
        return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1, r + 1))
    return over * pow(under, m - 2, m) cmb b = map(int, input().split()) map(int, input().split()) b n, a, b = map(int, input().split()) map(int, input().split()) n a, b = map(int, input().split()) map(int, input().split()) a
#!/usr/bin/env python3
from functools import reduce

mod = 10**9 + 7


def cmb(n, r, m):
    def mul(a, b):
        return a * b % m

    r = min(n - r, r)
    if r == 0:
        return 1
    over = reduce(mul, range(n, n - r, -1))
    under = reduce(mul, range(1, r + 1))
    return over * pow(under, m - 2, m)


n, a, b = map(int, input().split())
print((pow(2, n, mod) - 1 - cmb(n, a, mod) - cmb(n, b, mod)) % mod)
