#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  t = 1;
  long long int fact[22];
  fact[0] = fact[1] = 1;
  for (long long int i = 2; i <= 20; i++) fact[i] = fact[i - 1] * i;
  while (t--) {
    long long int n;
    cin >> n;
    cout << fact[n] / (long long int)pow(n / 2, 2) / 2 << "\n";
  }
}
