#include <bits/stdc++.h>
using namespace std;
void solve() {
  int64_t ans = 1;
  int64_t fac[21];
  fac[0] = 1;
  for (int i = 1; i <= 20; i++) {
    fac[i] = fac[i - 1] * i;
  }
  int n;
  cin >> n;
  int64_t choose = fac[n] / (fac[n / 2] * fac[n / 2]);
  ans *= choose;
  ans *= fac[n / 2 - 1];
  ans *= fac[n / 2 - 1];
  ans /= 2;
  cout << ans << "\n";
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  solve();
}
