#include <iostream>
using namespace std;

int main()
{
	int N; cin >> N;
	if (N == 1) {
		cout << 'O' << endl;
		return 0;
	}
	N += 1;

	while(N%2==0)N /= 2;

	cout << (N==1?'X':'O') << endl;

	return 0;
}