#include <algorithm>
#include <iomanip>
#include <istream>
#include <map>
#include <numeric>
#include <ostream>
#include <set>
#include <sstream>
#include <string>
#include <utility>
#include <vector>
using namespace std;
// Powered by caide (code generator, tester, and library code inliner)


class Solution {
public:
    void solve(std::istream& in, std::ostream& out) {
        unsigned long n;
        in >> n;
        n = (n % 10) == 1 ? 2 : (n % 10);
        out << (n % 2 == 0 ? "O" : "X");
    }
};

void solve(std::istream& in, std::ostream& out)
{
    out << std::setprecision(12);
    Solution solution;
    solution.solve(in, out);
}


#include <fstream>
#include <iostream>


int main() {
    
    ios_base::sync_with_stdio(0);
    cin.tie(0);


    istream& in = cin;


    ostream& out = cout;

    solve(in, out);
    return 0;
}