package no524;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		boolean zero = true;
		for(int i=0;i<=31;i++) {
			long cycle = (n+1) / (1L << (i+1));
			long reminder = (n+1) - cycle * (1L << (i+1));
			long sum = cycle * (1L << i) + Math.max(0, reminder - (1L << i));
			if (sum % 2 == 1) {
				zero = false;
				break;
			}
		}
		System.out.println(zero ? "X" : "O");
	}
	
	public static void test() {
		long sum = 0;
		for(long i=0;i<1000;i++) {
			sum ^= i;
			if (sum == 0) {
				System.out.println(Long.toBinaryString(i));
			}
		}
	}

}