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>
const double pi = 3.1415926535897;
using namespace std;
int n, m, t;
int binCoff(int nn, int k) {
  int C[nn + 1][k + 1];
  int i, j;
  for (i = 0; i <= nn; i++) {
    for (j = 0; j <= min(i, k); j++) {
      if (j == 0 || j == i)
        C[i][j] = 1;
      else
        C[i][j] = C[i - 1][j - 1] + C[i - 1][j];
    }
  }
  return C[nn][k];
}
long long int fact(long long int n) {
  long long int ans = 1;
  for (long long int i = 2; i <= n; i++) {
    ans *= i;
  }
  return ans;
}
long long int comb(int rG, int rB) {
  long long int ans = binCoff(n, rB);
  ans *= binCoff(m, rG);
  return ans;
}
int main() {
  cin >> n >> m >> t;
  long long int ans = 0;
  for (long long int nStart = 4; nStart <= n; nStart++) {
    for (long long int mStart = 1; mStart <= m; mStart++) {
      if (nStart + mStart != t) continue;
      ans += comb(mStart, nStart);
    }
  }
  cout << ans;
}
