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 comb(m, n):
    if m == 0 or n == m:
        return 1
    num = 1
    for i in range(1, n + 1):
        num *= i
    den = 1
    for i in range(1, m + 1):
        den *= i
    for i in range(1, n - m + 1):
        den *= i
    return int(num / den)


def main():
    line = input()
    l = line.split(' ')
    for i in range(0, len(l)):
        l[i] = int(l[i])
    n = l[0]
    m = l[1]
    t = l[2]
    ans = 0
    for b in range(4, n + 1):
        g = t - b
        if g < 1 or g > m:
            continue
        ans += comb(b, n) * comb(g, m)        
    print(int(ans))

if __name__ == "__main__":
    main()