There are n boys and m girls attending a theatre club. To set a play "The Big Bang Theory", they need to choose a group containing exactly t actors containing no less than 4 boys and no less than one girl. How many ways are there to choose a group? Of course, the variants that only differ in the composition of the troupe are considered different.

Perform all calculations in the 64-bit type: long long for С/С++, int64 for Delphi and long for Java.

Input

The only line of the input data contains three integers n, m, t (4 ≤ n ≤ 30, 1 ≤ m ≤ 30, 5 ≤ t ≤ n + m).

Output

Find the required number of ways.

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specificator.

Examples

Input

5 2 5


Output

10


Input

4 3 5


Output

3
def nck(n, k):
    res = 1
    for i in range(n-k+1, n+1):
        res *= i

    for i in range(2, k+1):
        res //= i

    return res


def main():
    n, m, t = map(int, input().split())
    ways = 0
    for boys in range(4, min(t-1, n)+1):
        girls = t - boys
        if 1 <= girls <= m:
            ways += nck(n, boys) * nck(m, girls)


    print(ways)


if __name__ == "__main__":
    main()