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

mod = 10**9+7





def extgcd(a, b):

    r = [1, 0, a]

    w = [0, 1, b]

    while w[2] != 1:

        q = r[2]//w[2]

        r2 = w

        w2 = [r[0]-q*w[0], r[1]-q*w[1], r[2]-q*w[2]]

        r = r2

        w = w2

    # [x,y]

    return [w[0], w[1]]





def mod_inv(a, m):

    x = extgcd(a, m)[0]

    return (m+x % m) % m





def comb(n, r, mod):

    u = 1

    d = 1

    for i in range(r):

        u *= n-i

        d *= i+1

        if u >= mod:

            u %= mod

        if d >= mod:

            d %= mod

    return u*mod_inv(d, mod)





def binary(n):

    return bin(n)[2:]





def pow_by_binary_exponentiation(a, x, n):  # a^x mod n

    x = [int(b) for b in binary(x)]

    y = a

    for i in range(1, len(x)):

        y = (y**2) % n

        if x[i] == 1:

            y = (y * a) % n

    return y





ac = comb(n, a, mod)

bc = comb(n, b, mod)

ans = pow_by_binary_exponentiation(2, n, mod)

print((((ans - ac - bc - 1) % mod)//1))

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

mod = 10**9+7





def binary(n):

    return bin(n)[2:]





# a^x mod n : ans = pow_by_binary_exponentiation(2, 1000, 10**9+7)

def pow_by_binary_exponentiation(a, x, n):

    x = [int(b) for b in binary(x)]

    y = a

    for i in range(1, len(x)):

        y = (y**2) % n

        if x[i] == 1:

            y = (y * a) % n

    return y





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

    n1, r = n+1, min(r, n-r)

    numer = denom = 1

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

        numer = numer * (n1-i) % mod

        denom = denom * i % mod

    return numer * pow(denom, mod-2, mod) % mod





ac = combination(n, a, mod)

bc = combination(n, b, mod)

ans = pow_by_binary_exponentiation(2, n, mod)

print((((ans - ac - bc - 1) % mod)//1))

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7


def extgcd(a, b):
    r = [1, 0, a]
    w = [0, 1, b]
    while w[2] != 1:
        q = r[2] // w[2]
        r2 = w
        w2 = [r[0] - q * w[0], r[1] - q * w[1], r[2] - q * w[2]]
        r = r2
        w = w2
    # [x,y]
    return [w[0], w[1]]


def mod_inv(a, m):
    x = extgcd(a, m)[0]
    return (m + x % m) % m


def comb(n, r, mod):
    u = 1
    d = 1
    for i in range(r):
        u *= n - i
        d *= i + 1
        if u >= mod:
            u %= mod
        if d >= mod:
            d %= mod
    return u * mod_inv(d, mod)


def binary(n):
    return bin(n)[2:]


def pow_by_binary_exponentiation(a, x, n):  # a^x mod n
    x = [int(b) for b in binary(x)]
    y = a
    for i in range(1, len(x)):
        y = (y**2) % n
        if x[i] == 1:
            y = (y * a) % n
    return y


ac = comb(n, a, mod)
bc = comb(n, b, mod)
ans = pow_by_binary_exponentiation(2, n, mod)
print((((ans - ac - bc - 1) % mod) // 1))

n, a, b = list(map(int, input().split()))
mod = 10**9 + 7


def binary(n):
    return bin(n)[2:]


# a^x mod n : ans = pow_by_binary_exponentiation(2, 1000, 10**9+7)
def pow_by_binary_exponentiation(a, x, n):
    x = [int(b) for b in binary(x)]
    y = a
    for i in range(1, len(x)):
        y = (y**2) % n
        if x[i] == 1:
            y = (y * a) % n
    return y


def combination(n, r, mod=10**9 + 7):
    n1, r = n + 1, min(r, n - r)
    numer = denom = 1
    for i in range(1, r + 1):
        numer = numer * (n1 - i) % mod
        denom = denom * i % mod
    return numer * pow(denom, mod - 2, mod) % mod


ac = combination(n, a, mod)
bc = combination(n, b, mod)
ans = pow_by_binary_exponentiation(2, n, mod)
print((((ans - ac - bc - 1) % mod) // 1))

- - -def extgcd(a, b): -    r = [1, 0, a] -    w = [0, 1, b] -    while w[2] != 1: -        q = r[2] // w[2] -        r2 = w -        w2 = [r[0] - q * w[0], r[1] - q * w[1], r[2] - q * w[2]] -        r = r2 -        w = w2 -    # [x,y] -    return [w[0], w[1]] - - -def mod_inv(a, m): -    x = extgcd(a, m)[0] -    return (m + x % m) % m - - -def comb(n, r, mod): -    u = 1 -    d = 1 -    for i in range(r): -        u *= n - i -        d *= i + 1 -        if u >= mod: -            u %= mod -        if d >= mod: -            d %= mod -    return u * mod_inv(d, mod) -def pow_by_binary_exponentiation(a, x, n):  # a^x mod n +# a^x mod n : ans = pow_by_binary_exponentiation(2, 1000, 10**9+7) +def pow_by_binary_exponentiation(a, x, n): -ac = comb(n, a, mod) -bc = comb(n, b, mod) +def combination(n, r, mod=10**9 + 7): +    n1, r = n + 1, min(r, n - r) +    numer = denom = 1 +    for i in range(1, r + 1): +        numer = numer * (n1 - i) % mod +        denom = denom * i % mod +    return numer * pow(denom, mod - 2, mod) % mod + + +ac = combination(n, a, mod) +bc = combination(n, b, mod)