def cmb(n, r, p):

    # nume/deno === nume * pow(deno, p - 2, p) (mod p)

    nume, deno = 1, 1

    for i in range(r):

        nume = nume * (n - i) % p

        deno = deno * (i + 1) % p

    return nume * pow(deno, p - 2, p) % p





if __name__ == "__main__":

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

    p = 10 ** 9 + 7



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

def comb(n, r, p):

    num, den = 1, 1

    r = min(r, n - r)

    for i in range(1, r + 1):

        num = num * (n - i + 1) % p

        den = den * i % p

    return num * pow(den, p - 2, p) % p





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

MOD = 1_000_000_007

ans = pow(2, n, MOD)

ans %= MOD

ans -= comb(n, a, MOD)

ans %= MOD

ans -= comb(n, b, MOD)

ans %= MOD

ans -= 1

ans %= MOD

print(ans)

def cmb(n, r, p):
    # nume/deno === nume * pow(deno, p - 2, p) (mod p)
    nume, deno = 1, 1
    for i in range(r):
        nume = nume * (n - i) % p
        deno = deno * (i + 1) % p
    return nume * pow(deno, p - 2, p) % p


if __name__ == "__main__":
    n, a, b = list(map(int, input().split()))
    p = 10**9 + 7
    print(((pow(2, n, p) - cmb(n, a, p) - cmb(n, b, p) - 1) % p))

def comb(n, r, p):
    num, den = 1, 1
    r = min(r, n - r)
    for i in range(1, r + 1):
        num = num * (n - i + 1) % p
        den = den * i % p
    return num * pow(den, p - 2, p) % p


n, a, b = list(map(int, input().split()))
MOD = 1_000_000_007
ans = pow(2, n, MOD)
ans %= MOD
ans -= comb(n, a, MOD)
ans %= MOD
ans -= comb(n, b, MOD)
ans %= MOD
ans -= 1
ans %= MOD
print(ans)

-def cmb(n, r, p): -    # nume/deno === nume * pow(deno, p - 2, p) (mod p) -    nume, deno = 1, 1 -    for i in range(r): -        nume = nume * (n - i) % p -        deno = deno * (i + 1) % p -    return nume * pow(deno, p - 2, p) % p +def comb(n, r, p): +    num, den = 1, 1 +    r = min(r, n - r) +    for i in range(1, r + 1): +        num = num * (n - i + 1) % p +        den = den * i % p +    return num * pow(den, p - 2, p) % p -if __name__ == "__main__": -    n, a, b = list(map(int, input().split())) -    p = 10**9 + 7 -    print(((pow(2, n, p) - cmb(n, a, p) - cmb(n, b, p) - 1) % p)) +n, a, b = list(map(int, input().split())) +MOD = 1_000_000_007 +ans = pow(2, n, MOD) +ans %= MOD +ans -= comb(n, a, MOD) +ans %= MOD +ans -= comb(n, b, MOD) +ans %= MOD +ans -= 1 +ans %= MOD +print(ans)