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

int main( int argc, char *argv[] )
{
long long N;

	ios::sync_with_stdio( false );
	cin.tie( 0 );

	cin >> N;
	if( N % 2 == 1 )
		cout << "X" << endl;
	else
		cout << "O" << endl;

	return 0;
}