import java.util.concurrent.CountDownLatch;

public class CDDemo
{
    public static void main(String[] args)
    {
        CountDownLatch cd = new CountDownLatch(3);
    
        new Racer(cd, "A").start();
        new Racer(cd, "B").start();
        new Racer(cd, "C").start();
        
        for(int i=0; i<3; i++)
        {
            try
            {
                Thread.sleep(1000);
                cd.countDown();
            }
            catch (InterruptedException e)
            {
                e.printStackTrace();
            }
            
            System.out.println(i);
        
            if(i == 2)
                System.out.println("start");
        }
        
    }
}
class Racer extends Thread
{
    private CountDownLatch countDownLatch;
    
    public Racer(CountDownLatch countDownLatch, String name)
    {
        setName(name);
        this.countDownLatch = countDownLatch;
    }
    @Override
    public void run()
    {
        try
        {
                countDownLatch.wait();
        }
        catch (InterruptedException e1)
        {
            e1.printStackTrace();
        }
        for(int i=0; i<3; i++)
        {
            System.out.println(getName()+" : "+i);
        }
    }
}