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;
const int N = 30;
int n, m, t;
long long c[N + 2][N + 2];
int main() {
  cin >> n >> m >> t;
  for (__typeof(0) i = (0) - ((0) > (N + 1)); i != (N + 1) - ((0) > (N + 1));
       i += 1 - 2 * ((0) > (N + 1)))
    fill(c[i], c[i] + N + 1, 1);
  for (__typeof(1) i = (1) - ((1) > (N)); i != (N) - ((1) > (N));
       i += 1 - 2 * ((1) > (N)))
    for (__typeof(i + 1) j = (i + 1) - ((i + 1) > (N + 1));
         j != (N + 1) - ((i + 1) > (N + 1)); j += 1 - 2 * ((i + 1) > (N + 1)))
      c[i][j] = c[i][j - 1] + c[i - 1][j - 1];
  long long res = 0;
  for (__typeof(4) i = (4) - ((4) > (n + 1)); i != (n + 1) - ((4) > (n + 1));
       i += 1 - 2 * ((4) > (n + 1))) {
    int j = t - i;
    if (j >= 1 and j <= m) res += c[i][n] * c[j][m];
  }
  cout << res << endl;
  return 0;
}
