public class CW implements Runnable {
    private static int count = 0;
    private int n = count++;
    private static Thread[] task = new Thread[3];
    public void run() {
        try { task[(n+1) % 3].join(); }
        catch (InterruptedException e) {
            System.err.println(e.toString());
        }
    }
    public static void main(String[] args) {
        for(int i=0; i<3; i++) 
            task[i] = new Thread(new CW());
        for(int i=0; i<3; i++) task[i].start();
    }
} // end of class CW