#include <cmath>
#include <string>
#include <vector>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <functional>
#pragma warning(disable : 4996)
using namespace std;
long long n;
int main() {
	cin >> n;
	if (n == 1) cout << "O" << endl;
	else {
		long long b = 1;
		while (b < n) b *= 2;
		cout << (b == n + 1 ? "X" : "O") << endl;
	}
	return 0;
}