#include<iostream>
using namespace std;


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