#include <bits/stdc++.h>
using namespace std;
const int N = 21;
long long f[N];
int main() {
  int n;
  cin >> n;
  f[0] = 1;
  for (int i = 1; i < N; ++i) {
    f[i] = f[i - 1] * i;
  }
  long long ans = f[n] / f[n / 2] / f[n / 2];
  ans = ans * f[n / 2 - 1];
  ans = ans * f[n / 2 - 1];
  ans /= 2;
  cout << ans << endl;
  return 0;
}
