#include <bits/stdc++.h>
using namespace std;
void c_p_c() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
long long fact(int n) {
  if (n == 1 || n == 0) {
    return 1;
  } else {
    return n * fact(n - 1);
  }
}
int32_t main() {
  c_p_c();
  int n;
  cin >> n;
  long long fac = fact(n);
  long long fac2 = fact(n / 2);
  long long round = fact(n / 2 - 1);
  long long choose = fac / (fac2 * fac2);
  long long ans = (choose * round * round) / 2;
  cout << ans << endl;
  return 0;
}
