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 dp[31][31];
unsigned long long solve(unsigned long long n, unsigned long long r) {
  if (n == r) return 1;
  if (r == 1) return n;
  unsigned long long &ret = dp[n][r];
  if (ret != -1) return ret;
  return ret = solve(n - 1, r) + solve(n - 1, r - 1);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  unsigned long long n, m, t, ans = 0;
  cin >> n >> m >> t;
  vector<pair<unsigned long long, unsigned long long> > V;
  unsigned long long b, g;
  if (n >= t) {
    b = t - 1, g = 1;
  } else {
    b = n, g = t - n;
  }
  while (b >= 4) {
    if (b + g <= t && b <= n && g <= m) V.push_back({b, g});
    b--, g++;
  }
  for (int i = 0; i < V.size(); i++) {
    memset(dp, -1, sizeof dp);
    unsigned long long a = solve(n, V[i].first);
    memset(dp, -1, sizeof dp);
    unsigned long long b = solve(m, V[i].second);
    ans += (a * b);
  }
  cout << ans << endl;
  return 0;
}
