#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long n, fact = 1;
  cin >> n;
  for (long long i = 2; i <= n; i++) {
    fact *= i;
  }
  long long ans = (2 * fact) / (n * n);
  cout << ans;
  return 0;
}
