#include <bits/stdc++.h>
using namespace std;
long long n;
int main() {
  cin >> n;
  long long ans = 1;
  for (long long i = n / 2 + 1; i < n + 1; i++) ans *= i;
  long long ans1 = 1;
  for (long long i = 1; i < n / 2 + 1; i++) ans1 *= i;
  long long ans3 = ans1 / (n / 2);
  cout << (ans / ans1) * ans3 * ans3 / 2 << endl;
  return 0;
}
