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 Pi = acos(-1.0);
const long double Eps = 1e-10;
bool u[31];
long long c(long long n, long long k) {
  memset(u, 0, sizeof(u));
  long long m = n - k, res = 1;
  if (k < m) swap(k, m);
  for (long long i = k + 1; i <= n; i++) {
    res *= i;
    for (long long j = 1; j <= m; j++)
      if (!u[j] && (res % j == 0)) {
        res /= j;
        u[j] = true;
      }
  }
  return res;
}
int main() {
  long long n, m, t, ans = 0;
  cin >> n >> m >> t;
  if (n < 4 || m < 1 || t < 5) {
    cout << 0 << endl;
    return 0;
  }
  for (long long b = 4; b < t; b++)
    if (t - b <= m && b <= n) ans += c(n, b) * c(m, t - b);
  cout << ans << endl;
  return 0;
}
