#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n;
  long long int fact = 1;
  cin >> n;
  if (n == 2)
    cout << 1 << endl;
  else {
    for (int i = 1; i <= n; i++) {
      fact = fact * i;
    }
    fact = 2 * fact / (n * n);
    cout << fact << endl;
  }
}
