#include "bits/stdc++.h"
using namespace std;

#define rep(i, n) for (int i = 0; i < (n); i ++)

int main() {
        long long n;
        cin >> n;
        n ++;
        while (n % 2 == 0) {
                n /= 2;
        }
        if (n == 1) cout << "X" << endl;
        else cout << "O" << endl;
        return 0;
}