from functools import reduce

stdin = open(0)
N, A, B = map(int, stdin.read().split())
MOD = 10 ** 9 + 7


def f(A):
    num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, A + 1))
    return num * pow(den, MOD - 2, MOD) % MOD


answer = pow(2, N, MOD) - f(A) - f(B) - 1
answer %= MOD
print(answer) from functools import reduce stdin = open(0) stdin open(0) open 0 N, A, B = map(int, stdin.read().split()) N map(int, stdin.read().split()) map int stdin.read().split() stdin.read().split stdin.read() stdin.read stdin read split A B MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 def f(A):
    num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, A + 1))
    return num * pow(den, MOD - 2, MOD) % MOD f num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1)) num 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 den = reduce(lambda x, y: x * y % MOD, range(1, A + 1)) den 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 num * pow(den, MOD - 2, MOD) % MOD num * pow(den, MOD - 2, MOD) % MOD num * pow(den, MOD - 2, MOD) num pow(den, MOD - 2, MOD) pow den MOD - 2 MOD 2 MOD MOD A A answer = pow(2, N, MOD) - f(A) - f(B) - 1 answer 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 answer %= MOD answer MOD print(answer) print answer answer = pow(2, N, MOD) - f(A) - f(B) - 1 pow(2, N, MOD) - f(A) - f(B) - 1 answer answer %= MOD MOD answer N, A, B = map(int, stdin.read().split()) map(int, stdin.read().split()) N A, B = map(int, stdin.read().split()) map(int, stdin.read().split()) A MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD stdin = open(0) open(0) stdin B = map(int, stdin.read().split()) map(int, stdin.read().split()) B def f(A):
    num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, A + 1))
    return num * pow(den, MOD - 2, MOD) % MOD def f(A):
    num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, A + 1))
    return num * pow(den, MOD - 2, MOD) % MOD f
from functools import reduce

stdin = open(0)
N, A, B = map(int, stdin.read().split())
MOD = 10 ** 9 + 7


def f(A):
    num = reduce(lambda x, y: x * y % MOD, range(N, N - A, -1))
    den = reduce(lambda x, y: x * y % MOD, range(1, A + 1))
    return num * pow(den, MOD - 2, MOD) % MOD


answer = pow(2, N, MOD) - f(A) - f(B) - 1
answer %= MOD
print(answer)
