Everything is working with 4 and with 3. But Validator doesn't want to accepting it... is anything wrong with that? Any explanation will help.. package com.codegym.task.task16.task1617; /* Countdown at the races */ public class Solution { public static volatile int numSeconds = 3; public static void main(String[] args) throws InterruptedException { RacingClock clock = new RacingClock(); //write your code here Thread.sleep(3500); clock.interrupt(); } public static class RacingClock extends Thread { public RacingClock() { start(); } public void run() { //write your code here if(numSeconds<3.5) { for (int i = numSeconds; i > 0; i--) { System.out.print(numSeconds + " "); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } numSeconds--; if(i==1) { System.out.print("GO!"); } } } else { for (int i = numSeconds; i > 0; i--) { System.out.print(numSeconds + " "); try { Thread.sleep(1000); } catch (InterruptedException e) { e.printStackTrace(); } numSeconds--; if(i==1) { System.out.print("Interrupted!"); Thread.currentThread().interrupt(); } } } } } }