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;
template <class T>
inline T sqr(const T& x) {
  return x * x;
}
template <class T>
inline void checkmin(T& a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T& a, T b) {
  if (b > a) a = b;
}
const double eps = 1e-8;
inline int dcmp(double x) { return x < -eps ? -1 : x > eps; }
inline bool deq(double x, double y) { return dcmp(x - y) == 0; }
inline bool dleq(double x, double y) { return dcmp(x - y) <= 0; }
long long pascal[31][33];
void calc_pascal() {
  pascal[0][1] = 1;
  for (int i = 1; i <= 30; i++)
    for (int j = 1; j <= i + 1; j++)
      pascal[i][j] = pascal[i - 1][j - 1] + pascal[i - 1][j];
}
long long comb(int n, int k) {
  if (n < 0) return 0;
  if (k < 0) return 0;
  if (k > n) return 0;
  return pascal[n][k + 1];
}
int n, m, t;
int main() {
  calc_pascal();
  cin >> n >> m >> t;
  long long res = 0;
  for (int i = 4; i <= t - 1; i++) res += comb(n, i) * comb(m, t - i);
  cout << res << endl;
  return 0;
}
