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>
template <typename T, typename U>
inline void swap(T &a, U &b) {
  a = a ^ b;
  b = a ^ b;
  a = a ^ b;
}
inline void swap(int &a, int &b) {
  a = a ^ b;
  b = a ^ b;
  a = a ^ b;
}
inline void smax(int &a, int b) {
  if (b > a) a = b;
}
inline void smin(int &a, int b) {
  if (b < a) a = b;
}
inline int gcd(int a, int b) {
  if (a < b) swap(a, b);
  while (b > 0) {
    a -= a / b * b;
    swap(a, b);
  }
  return a;
}
long long nchose(int a, int b) {
  long long ans = 1;
  smax(a, b - a);
  int p = 2;
  for (int i = (b - a + 1); i <= (b); i++) {
    ans *= (long long)i;
    while (p <= a && ans % p == 0) ans /= p++;
  }
  return ans;
}
using namespace std;
long long n, m, t;
int main() {
  cin >> n >> m >> t;
  long long ans = 0;
  for (int i = (4); i <= (n); i++) {
    int j = t - i;
    if (j < 1 || j > m) continue;
    ans += nchose(i, n) * nchose(j, m);
  }
  cout << ans;
}
