import sys
import math
from collections import deque

sys.setrecursionlimit(1000000)
MOD = 10 ** 9 + 7
input = lambda: sys.stdin.readline().strip()
NI = lambda: int(input())
NMI = lambda: map(int, input().split())
NLI = lambda: list(NMI())
SI = lambda: input()


def combinations_mod(n, r, mod=1000000007):
    """Returns nCr in mod."""
    r = min(r, n - r)
    combs = 1
    for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
    return combs


def main():
    n, a, b = NMI()
    all = pow(2, n, MOD) - 1
    ans = all - combinations_mod(n, a) - combinations_mod(n, b)
    ans %= MOD
    print(ans)



if __name__ == "__main__":
    main() import sys sys import math math from collections import deque sys.setrecursionlimit(1000000) sys.setrecursionlimit sys setrecursionlimit 1000000 MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 input = lambda: sys.stdin.readline().strip() input lambda: sys.stdin.readline().strip() sys.stdin.readline().strip() sys.stdin.readline().strip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline strip NI = lambda: int(input()) NI lambda: int(input()) int(input()) int input() input NMI = lambda: map(int, input().split()) NMI lambda: map(int, input().split()) map(int, input().split()) map int input().split() ().split () input split NLI = lambda: list(NMI()) NLI lambda: list(NMI()) list(NMI()) list NMI() NMI SI = lambda: input() SI lambda: input() input() input def combinations_mod(n, r, mod=1000000007):
    """Returns nCr in mod."""
    r = min(r, n - r)
    combs = 1
    for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
    return combs combinations_mod """Returns nCr in mod.""" r = min(r, n - r) r min(r, n - r) min r n - r n r combs = 1 combs 1 for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
     i j zip(range(n - r + 1, n + 1), range(1, r + 1)) zip range(n - r + 1, n + 1) range n - r + 1 n - r n r 1 n + 1 n 1 range(1, r + 1) range 1 r + 1 r 1 combs *= (i % mod) * pow(j, mod - 2, mod) combs (i % mod) * pow(j, mod - 2, mod) i % mod i mod pow(j, mod - 2, mod) pow j mod - 2 mod 2 mod combs %= mod combs mod return combs combs n n r r mod=1000000007 mod 1000000007 def main():
    n, a, b = NMI()
    all = pow(2, n, MOD) - 1
    ans = all - combinations_mod(n, a) - combinations_mod(n, b)
    ans %= MOD
    print(ans) main n, a, b = NMI() n NMI() NMI a b all = pow(2, n, MOD) - 1 all pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 ans = all - combinations_mod(n, a) - combinations_mod(n, b) ans all - combinations_mod(n, a) - combinations_mod(n, b) all - combinations_mod(n, a) all combinations_mod(n, a) combinations_mod n a combinations_mod(n, b) combinations_mod n b ans %= MOD ans MOD print(ans) print ans if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD input = lambda: sys.stdin.readline().strip() lambda: sys.stdin.readline().strip() input NMI = lambda: map(int, input().split()) lambda: map(int, input().split()) NMI NLI = lambda: list(NMI()) lambda: list(NMI()) NLI def combinations_mod(n, r, mod=1000000007):
    """Returns nCr in mod."""
    r = min(r, n - r)
    combs = 1
    for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
    return combs def combinations_mod(n, r, mod=1000000007):
    """Returns nCr in mod."""
    r = min(r, n - r)
    combs = 1
    for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
    return combs combinations_mod SI = lambda: input() lambda: input() SI def main():
    n, a, b = NMI()
    all = pow(2, n, MOD) - 1
    ans = all - combinations_mod(n, a) - combinations_mod(n, b)
    ans %= MOD
    print(ans) def main():
    n, a, b = NMI()
    all = pow(2, n, MOD) - 1
    ans = all - combinations_mod(n, a) - combinations_mod(n, b)
    ans %= MOD
    print(ans) main NI = lambda: int(input()) lambda: int(input()) NI
import sys
import math
from collections import deque

sys.setrecursionlimit(1000000)
MOD = 10 ** 9 + 7
input = lambda: sys.stdin.readline().strip()
NI = lambda: int(input())
NMI = lambda: map(int, input().split())
NLI = lambda: list(NMI())
SI = lambda: input()


def combinations_mod(n, r, mod=1000000007):
    """Returns nCr in mod."""
    r = min(r, n - r)
    combs = 1
    for i, j in zip(range(n - r + 1, n + 1), range(1, r + 1)):
        combs *= (i % mod) * pow(j, mod - 2, mod)
        combs %= mod
    return combs


def main():
    n, a, b = NMI()
    all = pow(2, n, MOD) - 1
    ans = all - combinations_mod(n, a) - combinations_mod(n, b)
    ans %= MOD
    print(ans)



if __name__ == "__main__":
    main()