#include <bits/stdc++.h>
using namespace std;
long long factorial(long long n) {
  long long i = 0, answer = 1;
  for (i = 1; i <= n; i++) answer *= i;
  return answer;
}
void solve(long long n) {
  long long k = 0;
  long long y = (factorial(n / 2 - 1));
  long long output =
      (factorial(n)) / (factorial(n / 2) * factorial(n / 2)) * y * y / 2;
  cout << output << endl;
}
int main() {
  long long n;
  cin >> n;
  solve(n);
  return 0;
}
