#include <bits/stdc++.h>
using namespace std;
const long long maxn = 1000000;
long long fact[21];
void fill() {
  fact[0] = 1;
  for (long long i = 1; i <= 20; ++i) {
    fact[i] = fact[i - 1] * i;
  }
}
void solve() {
  fill();
  long long n;
  cin >> n;
  cout << (fact[n]) / ((n * n) / 2);
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr);
  long long t = 1;
  while (t--) {
    solve();
  }
}
