#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  long long int fac[21];
  fac[0] = 1;
  for (int i = 1; i < 21; ++i) {
    fac[i] = fac[i - 1] * i;
  }
  long long int ans = (fac[n]) / (fac[n / 2] * fac[n / 2]);
  ans *= fac[(n / 2) - 1];
  ans *= fac[(n / 2) - 1];
  ans = ans / 2;
  cout << ans << endl;
  return 0;
}
