#include <iostream>

using namespace std;
using LL = long long;
using ULL = unsigned long long;

int main() {
    LL N;
    cin >> N;

    int Nim = 0;
    LL i = 2;
    while (N > i) {
        LL on = ((N / i) % 2) == 1 ? N % i : 0;
        if (on % 2 == 1) {
            Nim = 1;
            break;
        }
        i <<= 1;
    }

    if (Nim) {
        cout << "X" << endl;
    } else {
        cout << "O" << endl;
    }
}