def comb_mod(n, r, mod):
    up = 1
    down = 1
    for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
    return ((up * pow(down, mod - 2, mod)) % mod)


def main():
    MOD = 10**9 + 7
    n, a, b = [int(x) for x in input().split()]

    result = pow(2, n, MOD) - 1
    a_cmb = comb_mod(n, a, MOD)
    b_cmb = comb_mod(n, b, MOD)

    result = (result - a_cmb) % MOD
    result = (result - b_cmb) % MOD

    print(result)


if __name__ == '__main__':
    main() def comb_mod(n, r, mod):
    up = 1
    down = 1
    for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
    return ((up * pow(down, mod - 2, mod)) % mod) comb_mod up = 1 up 1 down = 1 down 1 for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
     i range(r) range r up *= n - i up n - i n i up %= mod up mod down *= i + 1 down i + 1 i 1 down %= mod down mod return ((up * pow(down, mod - 2, mod)) % mod) (up * pow(down, mod - 2, mod)) % mod up * pow(down, mod - 2, mod) up pow(down, mod - 2, mod) pow down mod - 2 mod 2 mod mod n n r r mod mod def main():
    MOD = 10**9 + 7
    n, a, b = [int(x) for x in input().split()]

    result = pow(2, n, MOD) - 1
    a_cmb = comb_mod(n, a, MOD)
    b_cmb = comb_mod(n, b, MOD)

    result = (result - a_cmb) % MOD
    result = (result - b_cmb) % MOD

    print(result) main MOD = 10**9 + 7 MOD 10**9 + 7 10**9 10 9 7 int(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() int(x) int x n, a, b = [int(x) for x in input().split()] n [int(x) for x in input().split()] a b result = pow(2, n, MOD) - 1 result pow(2, n, MOD) - 1 pow(2, n, MOD) pow 2 n MOD 1 a_cmb = comb_mod(n, a, MOD) a_cmb comb_mod(n, a, MOD) comb_mod n a MOD b_cmb = comb_mod(n, b, MOD) b_cmb comb_mod(n, b, MOD) comb_mod n b MOD result = (result - a_cmb) % MOD result (result - a_cmb) % MOD result - a_cmb result a_cmb MOD result = (result - b_cmb) % MOD result (result - b_cmb) % MOD result - b_cmb result b_cmb MOD print(result) print result if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main def main():
    MOD = 10**9 + 7
    n, a, b = [int(x) for x in input().split()]

    result = pow(2, n, MOD) - 1
    a_cmb = comb_mod(n, a, MOD)
    b_cmb = comb_mod(n, b, MOD)

    result = (result - a_cmb) % MOD
    result = (result - b_cmb) % MOD

    print(result) def main():
    MOD = 10**9 + 7
    n, a, b = [int(x) for x in input().split()]

    result = pow(2, n, MOD) - 1
    a_cmb = comb_mod(n, a, MOD)
    b_cmb = comb_mod(n, b, MOD)

    result = (result - a_cmb) % MOD
    result = (result - b_cmb) % MOD

    print(result) main def comb_mod(n, r, mod):
    up = 1
    down = 1
    for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
    return ((up * pow(down, mod - 2, mod)) % mod) def comb_mod(n, r, mod):
    up = 1
    down = 1
    for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
    return ((up * pow(down, mod - 2, mod)) % mod) comb_mod
def comb_mod(n, r, mod):
    up = 1
    down = 1
    for i in range(r):
        up *= n - i
        up %= mod
        down *= i + 1
        down %= mod
    return ((up * pow(down, mod - 2, mod)) % mod)


def main():
    MOD = 10**9 + 7
    n, a, b = [int(x) for x in input().split()]

    result = pow(2, n, MOD) - 1
    a_cmb = comb_mod(n, a, MOD)
    b_cmb = comb_mod(n, b, MOD)

    result = (result - a_cmb) % MOD
    result = (result - b_cmb) % MOD

    print(result)


if __name__ == '__main__':
    main()
