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;
void give(long long int arr[], long long int x) {
  for (long long int i = 1; i <= x; i++) {
    arr[i] = arr[i - 1] * (x - i + 1);
    arr[i] /= i;
  }
}
int main() {
  long long int n, m, t, sum = 0;
  cin >> n >> m >> t;
  long long int arr1[n + 1], arr2[m + 1];
  arr1[0] = 1;
  arr2[0] = 1;
  give(arr1, n);
  give(arr2, m);
  long long int a = t - 1, b = 1;
  while (a >= 4) {
    if (a <= n and a >= 4 and b >= 1 and b <= m) {
      long long int p = arr1[a] * arr2[b];
      sum += p;
    }
    a--;
    b++;
  }
  cout << sum << endl;
}
