#include "bits/stdc++.h"

using namespace std;

static void solve()
{
  int n;
  cin >> n;
  if (!n) cout << "X\n";
  while(n > 3) {
    n -= 4;
  }
  if (n == 3) cout << "X\n";
  else cout << "O\n";
}

int main()
{
  ios::sync_with_stdio(false);
  cin.tie();
  solve();
}