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

mod = 10 ** 9 + 7



# 乗法のmod逆元 (mod-2乗)

def modinv(a, mod=10**9+7):

    return pow(a, mod-2, mod)



# nCr mod m

# modinvが必要

# rがn/2に近いと非常に重くなる

def combination(n, r, mod=10**9+7):

    r = min(r, n-r)

    res = 1

    for i in range(r):

        res = res * (n - i) * modinv(i+1, mod) % mod

    return res



ans = pow(2, n, mod)

ans -= combination(n,a) + combination(n,b) + 1



print((ans % mod))

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

mod = 10 ** 9 + 7



# 乗法のmod逆元 (mod-2乗)

def modinv(a, mod=10**9+7):

    return pow(a, mod-2, mod)



# nCr mod m

# modinvが必要

# rがn/2に近いと非常に重くなる

def combination(n, r, mod=10**9+7):

    r = min(r, n-r)

    x = 1

    y = 1

    for i in range(r):

        x *= (n - i)

        y *= (i + 1)

        x %= mod

        y %= mod

    return (x * modinv(y, mod)) % mod



ans = pow(2, n, mod)

ans -= combination(n,a) + combination(n,b) + 1



print((ans % mod))

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7
# 乗法のmod逆元 (mod-2乗)
def modinv(a, mod=10**9 + 7):
    return pow(a, mod - 2, mod)


# nCr mod m
# modinvが必要
# rがn/2に近いと非常に重くなる
def combination(n, r, mod=10**9 + 7):
    r = min(r, n - r)
    res = 1
    for i in range(r):
        res = res * (n - i) * modinv(i + 1, mod) % mod
    return res


ans = pow(2, n, mod)
ans -= combination(n, a) + combination(n, b) + 1
print((ans % mod))

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7
# 乗法のmod逆元 (mod-2乗)
def modinv(a, mod=10**9 + 7):
    return pow(a, mod - 2, mod)


# nCr mod m
# modinvが必要
# rがn/2に近いと非常に重くなる
def combination(n, r, mod=10**9 + 7):
    r = min(r, n - r)
    x = 1
    y = 1
    for i in range(r):
        x *= n - i
        y *= i + 1
        x %= mod
        y %= mod
    return (x * modinv(y, mod)) % mod


ans = pow(2, n, mod)
ans -= combination(n, a) + combination(n, b) + 1
print((ans % mod))

-    res = 1 +    x = 1 +    y = 1 -        res = res * (n - i) * modinv(i + 1, mod) % mod -    return res +        x *= n - i +        y *= i + 1 +        x %= mod +        y %= mod +    return (x * modinv(y, mod)) % mod