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 gcd(long long a, long long b) {
  if (a < b) swap(a, b);
  while (b) swap(a, b), b %= a;
  return a;
}
long long nCr(int n, int r) {
  int start = max(r, n - r) + 1;
  r = min(r, n - r);
  vector<int> numerator, dominator;
  for (int i = start; i <= (int)(n); ++i) numerator.push_back(i);
  for (int i = 0; i < (int)(r); ++i) {
    dominator.push_back(i + 1);
    for (int j = 0; j < (int)(((int)numerator.size())); ++j) {
      int common = gcd(numerator[j], dominator[i]);
      dominator[i] /= common, numerator[j] /= common;
    }
  }
  long long factorial_n = 1, factorial_d = 1;
  for (int i = 0; i < (int)(((int)numerator.size())); ++i)
    factorial_n *= numerator[i];
  for (int i = 0; i < (int)(((int)dominator.size())); ++i)
    factorial_d *= dominator[i];
  return factorial_n / factorial_d;
}
int main() {
  int n, m, t;
  cin >> n >> m >> t;
  long long res = 0;
  for (int i = 4; i <= (int)(n); ++i) {
    if (t - i < 1) break;
    if (t - i > m) continue;
    res += nCr(n, i) * nCr(m, (t - i));
  }
  cout << res;
  return 0;
}
