Q = 10**9+7



def getInv(N):

    inv = [0] * (N + 1)

    inv[1] = 1

    for i in range(2, N + 1):

        inv[i] = (-(Q // i) * inv[Q % i]) % Q

    return inv



def main():



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

    Inv = getInv(2*10**5)

    def cmb(n,r):

        ret = 1

        for i in range(r):

            ret *= n-i

            ret %= Q

            ret *= Inv[i+1]

            ret %= Q

        return ret

    print(( (pow(2,n,Q) - cmb(n,a) - cmb(n,b)-1)%Q))

if __name__ == '__main__':

    main()
Q = 10**9+7



def cmb(n,r):

    if n-r < r: r = n-r

    if r == 0: return 1

    denominator = 1                       #分母

    numerator = 1                         #分子

    for i in range(r):

        numerator *= n-i

        numerator %= Q

        denominator *= i+1

        denominator %= Q

    return numerator*pow(denominator, Q-2, Q)%Q



def main():

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

    print(( (pow(2,n,Q) - cmb(n,a) - cmb(n,b)-1)%Q))

if __name__ == '__main__':

    main()

Q = 10**9 + 7


def getInv(N):
    inv = [0] * (N + 1)
    inv[1] = 1
    for i in range(2, N + 1):
        inv[i] = (-(Q // i) * inv[Q % i]) % Q
    return inv


def main():
    n, a, b = list(map(int, input().split()))
    Inv = getInv(2 * 10**5)

    def cmb(n, r):
        ret = 1
        for i in range(r):
            ret *= n - i
            ret %= Q
            ret *= Inv[i + 1]
            ret %= Q
        return ret

    print(((pow(2, n, Q) - cmb(n, a) - cmb(n, b) - 1) % Q))


if __name__ == "__main__":
    main()

Q = 10**9 + 7


def cmb(n, r):
    if n - r < r:
        r = n - r
    if r == 0:
        return 1
    denominator = 1  # 分母
    numerator = 1  # 分子
    for i in range(r):
        numerator *= n - i
        numerator %= Q
        denominator *= i + 1
        denominator %= Q
    return numerator * pow(denominator, Q - 2, Q) % Q


def main():
    n, a, b = list(map(int, input().split()))
    print(((pow(2, n, Q) - cmb(n, a) - cmb(n, b) - 1) % Q))


if __name__ == "__main__":
    main()

-def getInv(N): -    inv = [0] * (N + 1) -    inv[1] = 1 -    for i in range(2, N + 1): -        inv[i] = (-(Q // i) * inv[Q % i]) % Q -    return inv +def cmb(n, r): +    if n - r < r: +        r = n - r +    if r == 0: +        return 1 +    denominator = 1  # 分母 +    numerator = 1  # 分子 +    for i in range(r): +        numerator *= n - i +        numerator %= Q +        denominator *= i + 1 +        denominator %= Q +    return numerator * pow(denominator, Q - 2, Q) % Q -    Inv = getInv(2 * 10**5) - -    def cmb(n, r): -        ret = 1 -        for i in range(r): -            ret *= n - i -            ret %= Q -            ret *= Inv[i + 1] -            ret %= Q -        return ret -