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