import sys

sys.setrecursionlimit(10**7)

input = sys.stdin.readline



mod = 10**9+7



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



def comb(n, k):

    c = 1

    for i in range(n - k + 1, n + 1):

        c *= i

        c %= mod



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

        c *= pow(i, mod - 2, mod)

        c %= mod



    return c



ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b)

print((ans % mod))

import sys

sys.setrecursionlimit(10**7)

input = sys.stdin.readline



mod = 10**9+7



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



# def comb(n, k):

#     c = 1

#     for i in range(n - k + 1, n + 1):

#         c *= i

#         c %= mod

#

#     for i in range(1, k + 1):

#         c *= pow(i, mod - 2, mod)

#         c %= mod

#

#     return c



def comb(n, k):

    c = 1

    for i in range(k):

        c *= n - i

        c %= mod



    d = 1

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

        d *= i

        d %= mod



    return (c * pow(d, mod - 2, mod)) % mod



ans = pow(2, n, mod) - 1 - comb(n, a) - comb(n, b)

print((ans % mod))

import sys

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


def comb(n, k):
    c = 1
    for i in range(n - k + 1, n + 1):
        c *= i
        c %= mod
    for i in range(1, k + 1):
        c *= pow(i, mod - 2, mod)
        c %= mod
    return c


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

import sys

sys.setrecursionlimit(10**7)
input = sys.stdin.readline
mod = 10**9 + 7
n, a, b = list(map(int, input().split()))
# def comb(n, k):
#     c = 1
#     for i in range(n - k + 1, n + 1):
#         c *= i
#         c %= mod
#
#     for i in range(1, k + 1):
#         c *= pow(i, mod - 2, mod)
#         c %= mod
#
#     return c
def comb(n, k):
    c = 1
    for i in range(k):
        c *= n - i
        c %= mod
    d = 1
    for i in range(1, k + 1):
        d *= i
        d %= mod
    return (c * pow(d, mod - 2, mod)) % mod


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

- - +# def comb(n, k): +#     c = 1 +#     for i in range(n - k + 1, n + 1): +#         c *= i +#         c %= mod +# +#     for i in range(1, k + 1): +#         c *= pow(i, mod - 2, mod) +#         c %= mod +# +#     return c -    for i in range(n - k + 1, n + 1): -        c *= i +    for i in range(k): +        c *= n - i +    d = 1 -        c *= pow(i, mod - 2, mod) -        c %= mod -    return c +        d *= i +        d %= mod +    return (c * pow(d, mod - 2, mod)) % mod