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
#include <bits/stdc++.h>
using namespace std;
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  unsigned long long res = 0;
  while (y > 0) {
    res = x % y;
    x = y;
    y = res;
  }
  return x;
}
unsigned long long c(unsigned long long n, unsigned long long k) {
  if (k > n / 2) k = n - k;
  unsigned long long res = 1;
  unsigned long long todiv = 1;
  unsigned long long tomul = 1;
  for (unsigned long long i = 0; i < k; i++) {
    todiv *= k - i;
    tomul *= n - i;
    unsigned long long gcde = gcd(todiv, tomul);
    todiv /= gcde;
    tomul /= gcde;
  }
  res *= tomul;
  res /= todiv;
  return res;
}
int main() {
  int n, m, t;
  cin >> n >> m >> t;
  unsigned long long res = 0;
  for (int i = 4; i <= n; i++) {
    if (t - i > 0 && t - i <= m) res += c(n, i) * c(m, t - i);
  }
  cout << res << endl;
  return 0;
}
