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 fac(n):
    m = 1
    for i in xrange(1, n+1):
        m *= i
    return m
if __name__=="__main__":
    n, m, t = [int(x) for x in raw_input().split()]
    bf = fac(n)
    gf = fac(m)

    s = 0
    for i in range(4, t):
        if t-i>m:
            continue;
        bc = (bf/(fac(n-i)*fac(i)))
        g = t-i
        gc = (gf/(fac(m-g)*fac(g)))
        s += (bc*gc)

    print s
