#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int t = 1;
  while (t--) {
    int n;
    cin >> n;
    unsigned long long int fact = 2;
    for (int i = 2; i < n; i++) {
      fact *= i;
    }
    cout << ((fact) / n) << endl;
  }
}
