#include <bits/stdc++.h>
using namespace std;
const long long int N = 2e5 + 7;
const long long int mod = 1e9 + 7;
void solve1() {
  long long int n;
  cin >> n;
  long long int s = 1;
  for (long long int i = 2; i <= n - 1; i++) s *= i;
  cout << s / (n / 2);
}
int32_t main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  srand(time(0));
  long long int cghf = 1;
  while (cghf--) {
    solve1();
  }
}
