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;
long long z, j, n, m, t, s = 0, i, a[30], b[30], x, y, k;
long long c(long long n, long long r) {
  z = 1;
  x = 0;
  y = 0;
  for (j = max(r, n - r) + 1; j <= n; j++) a[x++] = j;
  j = min(r, n - r);
  while (j) b[y++] = j--;
  for (k = 0; k < y; k++)
    for (j = x - 1; j >= 0; j--)
      if (a[j] % b[k] == 0) {
        a[j] /= b[k];
        b[k] = 1;
        break;
      }
  for (j = 0; j < x; j++) z *= a[j];
  for (j = 0; j < y; j++) z /= b[j];
  return z;
}
int main() {
  cin >> n >> m >> t;
  for (i = 4; i <= n; i++)
    if (t - i <= m && t - i > 0) s += c(n, i) * c(m, t - i);
  cout << s;
  return 0;
}
