#include <bits/stdc++.h>
using namespace std;
long long factorial(long long n) {
  if (n <= 1)
    return 1;
  else
    return n * factorial(n - 1);
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  long long result = factorial(n);
  result = result / (n * n / 2);
  cout << result << endl;
  return 0;
}
