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 pas[35][35];
void calcTriangle() {
  for (int i = 0; i < 35; i++) pas[i][i] = pas[i][0] = 1;
  for (int i = 1; i < 35; i++) pas[0][i] = 0;
  for (int i = 1; i < 35; i++)
    for (int j = 1; j < i; j++) pas[i][j] = pas[i - 1][j] + pas[i - 1][j - 1];
}
int main() {
  int n, m, t;
  long long b[35], g[35];
  long long res = 0;
  scanf("%d %d %d", &n, &m, &t);
  calcTriangle();
  memset(b, 0, sizeof(b));
  memset(g, 0, sizeof(g));
  for (int i = 4; i <= n; i++) b[i] += pas[n][i];
  for (int i = 1; i <= m; i++) g[i] += pas[m][i];
  int l = min(t - 1, n);
  for (int i = 4; i <= l; i++) {
    if (t - i <= m) res += b[i] * (g[t - i]);
  }
  printf("%I64d\n", res);
  return 0;
}
