#include <bits/stdc++.h>
using namespace std;
const int MOD = (int)1e9 + 7;
const int N = (int)1e5;
long long int f[21];
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  f[0] = 1;
  for (int i = 1; i <= 20; i++) {
    f[i] = f[i - 1] * i;
  }
  int n;
  cin >> n;
  long long int ans;
  ans = (2 * f[n]) / (n * n);
  cout << ans;
  return 0;
}
