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;
unsigned long long gcd(unsigned long long x, unsigned long long y) {
  while (y != 0) {
    unsigned long long t = x % y;
    x = y;
    y = t;
  }
  return x;
}
unsigned long long com(unsigned long long n, unsigned long long k) {
  if (k > n) return 0;
  unsigned long long r = 1;
  for (unsigned long long d = 1; d <= k; ++d, --n) {
    unsigned long long g = gcd(r, d);
    r /= g;
    unsigned long long t = n / (d / g);
    if (r > std::numeric_limits<unsigned long long>::max() / t) return 0;
    r *= t;
  }
  return r;
}
int main() {
  ios::sync_with_stdio(false);
  long long res = 0, boys, girls, t;
  cin >> boys >> girls >> t;
  for (int i = 4; i <= boys; i++) {
    for (int j = 1; j <= girls; j++) {
      if (i + j > t) break;
      if (i + j == t) res += com(boys, i) * com(girls, j);
    }
  }
  cout << res << endl;
}
