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 double eps = 0.0000001;
const int inf = 1e9 + 7;
const long long mod = 1e9 + 7;
const int maxn = 1e6 + 5;
long long c[100][100];
int vis[100][100];
int main() {
  long long n, m, t;
  cin >> n >> m >> t;
  memset(c, 0, sizeof(c));
  c[0][0] = 1;
  for (int i = 1; i <= 40; i++) {
    c[i][0] = 1;
    for (int j = 1; j <= i; j++) {
      c[i][j] = c[i - 1][j] + c[i - 1][j - 1];
    }
  }
  long long ans = 0;
  memset(vis, 0, sizeof(vis));
  for (int i = 4; i <= t - 1 && i <= n; i++) {
    ans += c[n][i] * c[m][t - i];
    vis[i][t - i] = 1;
  }
  for (int i = 1; i <= t - 4 && i <= m; i++) {
    if (!vis[t - i][i]) ans += c[m][i] * c[n][t - i];
  }
  cout << ans << endl;
}
