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 fack(n):
    if n == 0:
        return 1
    return reduce(lambda x,y: x*y, range(1,n+1))


n, m, t = [int(a) for a in raw_input().strip().split(' ')]

cnt = 0

for man_cnt in range(4, min(n, t-1)+1):
    girl_cnt = t - man_cnt

    if girl_cnt > m:
        continue
    #print man_cnt, girl_cnt, n-man_cnt, m-girl_cnt
    #print fack(n)/(fack(man_cnt)*fack(n-man_cnt))
    #print fack(m)/(fack(girl_cnt)*fack(m-girl_cnt))
    cnt += (fack(n)/(fack(man_cnt)*fack(n-man_cnt))*fack(m)/(fack(girl_cnt)*fack(m-girl_cnt)))

print cnt


#reduce(lambda x,y: x*y, range(1,6))

