mod = 1000000007

def mod_cmb(n: int, k: int, p: int) -> int:
    if n < 0 or k < 0 or n < k: return 0
    if n == 0 or k == 0: return 1
    if (k > n - k):
        return mod_cmb(n, n - k, p)
    c = d = 1
    for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
    return c * pow(d, -1, p) % p

def main():
    n, a, b = map(int, input().split())

    ans = pow(2, n, mod) - 1

    tmp_a = mod_cmb(n , a, mod)
    tmp_b = mod_cmb(n , b, mod)

    print((ans-tmp_a-tmp_b)%mod)

if __name__ == '__main__':
    main() mod = 1000000007 mod 1000000007 def mod_cmb(n: int, k: int, p: int) -> int:
    if n < 0 or k < 0 or n < k: return 0
    if n == 0 or k == 0: return 1
    if (k > n - k):
        return mod_cmb(n, n - k, p)
    c = d = 1
    for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
    return c * pow(d, -1, p) % p mod_cmb if n < 0 or k < 0 or n < k: return 0
     n < 0 or k < 0 or n < k n < 0 or k < 0 n < 0 n 0 k < 0 k 0 n < k n k if n == 0 or k == 0: return 1
     n == 0 or k == 0 n == 0 n 0 k == 0 k 0 if (k > n - k):
        return mod_cmb(n, n - k, p)
     k > n - k k n - k n k return mod_cmb(n, n - k, p) mod_cmb(n, n - k, p) mod_cmb n n - k n k p c = d = 1 c 1 = d = 1 d 1 for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
     i range(k) range k c *= (n - i) c n - i n i d *= (k - i) d k - i k i c %= p c p d %= p d p return c * pow(d, -1, p) % p c * pow(d, -1, p) % p c * pow(d, -1, p) c pow(d, -1, p) pow d -1 p p n: int n k: int k p: int p def main():
    n, a, b = map(int, input().split())

    ans = pow(2, n, mod) - 1

    tmp_a = mod_cmb(n , a, mod)
    tmp_b = mod_cmb(n , b, mod)

    print((ans-tmp_a-tmp_b)%mod) main n, a, b = map(int, input().split()) n map(int, input().split()) map int input().split() ().split () input split a b ans = pow(2, n, mod) - 1 ans pow(2, n, mod) - 1 pow(2, n, mod) pow 2 n mod 1 tmp_a = mod_cmb(n , a, mod) tmp_a mod_cmb(n , a, mod) mod_cmb n a mod tmp_b = mod_cmb(n , b, mod) tmp_b mod_cmb(n , b, mod) mod_cmb n b mod print((ans-tmp_a-tmp_b)%mod) print (ans-tmp_a-tmp_b)%mod ans-tmp_a-tmp_b ans-tmp_a ans tmp_a tmp_b mod if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main mod = 1000000007 1000000007 mod def mod_cmb(n: int, k: int, p: int) -> int:
    if n < 0 or k < 0 or n < k: return 0
    if n == 0 or k == 0: return 1
    if (k > n - k):
        return mod_cmb(n, n - k, p)
    c = d = 1
    for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
    return c * pow(d, -1, p) % p def mod_cmb(n: int, k: int, p: int) -> int:
    if n < 0 or k < 0 or n < k: return 0
    if n == 0 or k == 0: return 1
    if (k > n - k):
        return mod_cmb(n, n - k, p)
    c = d = 1
    for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
    return c * pow(d, -1, p) % p mod_cmb def main():
    n, a, b = map(int, input().split())

    ans = pow(2, n, mod) - 1

    tmp_a = mod_cmb(n , a, mod)
    tmp_b = mod_cmb(n , b, mod)

    print((ans-tmp_a-tmp_b)%mod) def main():
    n, a, b = map(int, input().split())

    ans = pow(2, n, mod) - 1

    tmp_a = mod_cmb(n , a, mod)
    tmp_b = mod_cmb(n , b, mod)

    print((ans-tmp_a-tmp_b)%mod) main
mod = 1000000007

def mod_cmb(n: int, k: int, p: int) -> int:
    if n < 0 or k < 0 or n < k: return 0
    if n == 0 or k == 0: return 1
    if (k > n - k):
        return mod_cmb(n, n - k, p)
    c = d = 1
    for i in range(k):
        c *= (n - i)
        d *= (k - i)
        c %= p
        d %= p
    return c * pow(d, -1, p) % p

def main():
    n, a, b = map(int, input().split())

    ans = pow(2, n, mod) - 1

    tmp_a = mod_cmb(n , a, mod)
    tmp_b = mod_cmb(n , b, mod)

    print((ans-tmp_a-tmp_b)%mod)

if __name__ == '__main__':
    main()
