#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n;
  cin >> n;
  long long fac[21];
  fac[1] = 1;
  for (int i = 2; i < 21; ++i) fac[i] = i * fac[i - 1];
  cout << (fac[n] * 2) / (n * n);
}
