#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>

#include <functional>
#include <cassert>

typedef long long ll;
using namespace std;

#define debug(x) cerr << #x << " = " << (x) << endl;


#define mod 1000000007 //1e9+7(prime number)
#define INF 1000000000 //1e9
#define LLINF 2000000000000000000LL //2e18
#define SIZE 100010


int main(){
  ll n,n2;

  cin >> n;
  n2 = n;

  ll t = 1;

  if(n == 0){
    puts("X");
    return 0;
  }
  
  for(int i=0;n2;i++){
    n2/=2;
    ll p = n%t;

    if((n2 + p)%2==0){
      puts("O");
      return 0;
    }
    
    t*=2;
  }

  puts("X");
  
  return 0;
}


/*
 11
 10
 01
 00
 */