#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  ;
  long long int temp = 1, flag = 1;
  for (int i = n; i > (n / 2); i--) {
    temp *= i;
  }
  for (int i = n / 2; i > 0; i--) {
    flag *= i;
  }
  long long int ans = (temp / flag) * (flag / (n / 2)) * (flag / (n / 2));
  long long int ans1 = ans / 2;
  cout << ans1;
  return 0;
}
