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 x1, out;
unsigned long long Fac(unsigned long long x1) {
  unsigned long long out = 1;
  for (int i = 1; i <= x1; i++) out = out * i;
  return out;
}
unsigned long long Cnk(unsigned long long a, unsigned long long b,
                       unsigned long long c) {
  unsigned long long outL = 1;
  vector<int> fac;
  if (b > c) {
    unsigned long long nCount = a - b;
    for (int i = 2; i <= c; i++) fac.push_back(i);
    while (nCount > 0) {
      outL = outL * a;
      a--;
      nCount--;
      for (int i = 0; i < fac.size(); i++) {
        if (fac[i] > -1 && outL % fac[i] == 0) {
          outL = outL / fac[i];
          fac[i] = -1;
        }
      }
    }
  } else {
    unsigned long long nCount = a - c;
    for (int i = 2; i <= b; i++) fac.push_back(i);
    while (nCount > 0) {
      outL = outL * a;
      a--;
      nCount--;
      for (int i = 0; i < fac.size(); i++) {
        if (fac[i] > -1 && outL % fac[i] == 0) {
          outL = outL / fac[i];
          fac[i] = -1;
        }
      }
    }
  }
  for (int i = 0; i < fac.size(); i++) {
    if (fac[i] > -1) outL = outL / fac[i];
  }
  return outL;
}
int main() {
  int n, m, t;
  cin >> n >> m >> t;
  for (int i = 4; i <= n; i++) {
    for (int y = 1; y <= m; y++) {
      if (i + y != t) continue;
      out += (Cnk(n, i, n - i) * Cnk(m, y, m - y));
    }
  }
  cout << out;
  cin >> x1;
}
