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 PI = acos(-1);
const int MAXN = 1e6;
unsigned long long comb(unsigned long long n, unsigned long long k) {
  if (k > n) return 0;
  unsigned long long u = 1;
  for (unsigned long long i = 1; i <= k; i++) {
    u *= n--;
    u /= i;
  }
  return u;
}
int main() {
  unsigned long long n, m, t;
  while (cin >> n >> m >> t) {
    unsigned long long ans = 0;
    for (unsigned long long boys = 4; boys <= n; boys++) {
      unsigned long long girls = t - boys;
      if (girls > m) continue;
      if (t < 1 + boys) break;
      ans += comb(n, boys) * comb(m, girls);
    }
    cout << ans << endl;
  }
  return 0;
}
