#include <bits/stdc++.h>
using namespace std;
bool cmp(const pair<int, int> &a, const pair<int, int> &b) {
  return (a.second > b.second);
}
void solve() {
  int n;
  cin >> n;
  unsigned long long cnt = 1;
  for (int i = 1; i < n; i++) {
    cnt *= i;
  }
  cnt /= n / 2;
  cout << cnt << endl;
}
int main() { solve(); }
