#include <bits/stdc++.h>
using namespace std;
long long int factorial(int n) {
  long long int fac = 1;
  for (int i = 1; i <= n; i++) fac *= i;
  return fac;
}
int main() {
  long long int n;
  cin >> n;
  long long int ans = 2 * factorial(n);
  long long int sq = n * n;
  ans /= sq;
  cout << ans << "\n";
  return 0;
}
