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