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
#! -*- coding: utf-8 -*-
import sys
def main():
  n, m, t = map(int, sys.stdin.readline().strip().split(' '))
  dp_boy = []
  dp_girl = []
  for i in range(0,n+1):
    tmp = [0 for j in range(i+1)]
    tmp[0] = tmp[-1] = 1
    dp_boy.append(tmp)
  for i in range(0,m+1):
    tmp = [0 for j in range(i+1)]
    tmp[0] = tmp[-1] = 1
    dp_girl.append(tmp)

  # print dp_boy
  # print dp_girl
  for i in xrange(2, n+1):
    for j in xrange(1, i):
      dp_boy[i][j] = dp_boy[i-1][j] + dp_boy[i-1][j-1]
  for i in xrange(2, m+1):
    for j in xrange(1, i):
      dp_girl[i][j] = dp_girl[i-1][j] + dp_girl[i-1][j-1]
  # print dp_boy
  # print dp_girl

  res = 0
  for i in range(4, n+1):
    for j in range(1, m+1):
      # print i, j, t
      if i+j == t:
        # print dp_boy[n][i], dp_girl[m][j]
        res += dp_boy[n][i] * dp_girl[m][j]
  print res
  
if __name__=='__main__':
  main()
