#include <bits/stdc++.h>
using namespace std;
void solve() {
  long long i, f = 1, n;
  cin >> n;
  for (i = 1; i < n; i++) f *= i;
  f *= 2;
  f = f / n;
  cout << f << "\n";
}
int main() {
  int t = 1;
  while (t--) solve();
}
