#include "bits/stdc++.h"

using namespace std;

static void solve()
{
  long long n;
  cin >> n;
  bitset<33> b(n + 1);
  if (b.count() == 1) cout << "X\n";
  else cout << "O\n";
}

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