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;
vector<string> token(string a) {
  vector<string> w;
  a.push_back(' ');
  while (!a.empty()) {
    w.push_back(a.substr(0, a.find(" ")));
    a = a.substr(a.find(" ") + 1, a.size() - 1);
  }
  return w;
}
map<string, int> mapik;
vector<string> amapik;
int dodaj(string a) {
  if (mapik.count(a) == 0) {
    mapik[a] = mapik.size() - 1;
    amapik.push_back(a);
  }
  return mapik[a];
}
char tmp_str[1000];
string scanf_string() {
  scanf("%s", tmp_str);
  return tmp_str;
}
const int N = 1000;
int n, m, t;
long long po(int n, int m) {
  if (m > n) return 0;
  long long res = 1;
  for (int i = 1; i <= m; i++) {
    res *= n - m + i;
    res /= i;
  }
  return res;
}
int main() {
  scanf("%d%d%d", &n, &m, &t);
  long long res = 0;
  for (int i = 4; i <= t - 1; i++) {
    res += po(n, i) * po(m, t - i);
  }
  printf("%I64d\n", res);
  return 0;
}
