import element.*;

public class SieveThread extends Thread
{
    private static final int max = 10000;  // largest prime reported
    private int fact;                      // factor we are sieve for
    private SieveThread nextSieve;         // reference to next sieve

    private boolean inputValid;
    private int input;

    public SieveThread()
    {
        inputValid = false;  // the input buffer isn't being used...yet
    }

    synchronized public int receive()
    // post: read a value from smaller SieveThread
    {
        while (!inputValid) 
        {
            try
            {
                wait();
            } catch (Exception e) { System.exit(0); }
        }
        inputValid = false;     // at return, input will be gobbled
        notify();               // wake up possible waiting sender
        return input;           // return soon-to-be invalid input
    }

    synchronized public void send(int n)
    // post: write n to larger SieveThread
    {
        while (inputValid)
        {
            try
            {
                wait();
            } catch (Exception e) { System.exit(0); }
        }
        input = n;              // we have the lock, set buffer
        inputValid = true;      // indicate that the buffer is useful
        notify();               // wake up receiver (if waiting)
    }

    public void run()
    {
        fact = receive();
        System.out.println(fact);
        int n;

        // start up next sieve in line
        nextSieve = new SieveThread();
        nextSieve.setPriority(Thread.NORM_PRIORITY-1);
        nextSieve.start();

        for (n = receive(); n < max; n = receive())
        {
            // read values and pass along ones that we don't divide
            if (0 != n % fact) {
                nextSieve.send(n);
            }
        }
    }

    public static void main(String args[])
    {
        // start up a sieve
        SieveThread source = new SieveThread();
        source.setPriority(Thread.NORM_PRIORITY-1);
        source.start();
        int i;
        for (i = 2; i < max; i++)
        {
            // send it a stream of integers
            source.send(i);
        }
    }
}