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
import math


def comb(n, r):
    p = 1
    k = n - r
    if r == 1:
        return n
    elif r == n:
        return 1
    elif r > k:
        while n > r:
            p = p*n
            n = n-1
        p = p/(math.factorial(k))
    else:
        while n > k:
            p = p*n
            n = n-1
        p = p/(math.factorial(r))
    return p


def main():
    a = [int(x) for x in input().strip().split(' ')]
    n = a[0]
    m = a[1]
    t = a[2]
    i = n
    j = m
    s = 0
    while i >= 4 and j >= 1:
        if (i >= 4) and (t-i >= 1) and i <= n and t-i <= m:
            l = int(comb(n, i))
            q = int(comb(m, t-i))
            l *= q
            s += l
        i = i-1
    print(s)
main()