#include <bits/stdc++.h>
using namespace std;
long long factorial(int n) {
  if (n == 1) return 1;
  if (n == 0)
    return 1;
  else
    return n * factorial(n - 1);
}
int main() {
  int n;
  cin >> n;
  if (n == 2)
    cout << "1\n";
  else
    cout << factorial(n - 1) / (n / 2) << '\n';
}
