#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n, f = 1;
  cin >> n;
  for (int i = 1; i <= n - 1; i++) {
    f *= i;
  }
  n /= 2;
  f /= n;
  cout << f << "\n";
}
