import java.util.Date;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;

public class Main {

    public static void main(String[] args) {

        for (int k = 0; k < 50; k++) {

            int numberOfThreads = k % 2 + 1;
            Date d1 = new Date();
            MyRunnable.numberOfThreads = numberOfThreads;
            MyRunnable.counter = new AtomicInteger(numberOfThreads);
            Thread[] threads = new Thread[numberOfThreads];
            for (int i = 0; i < threads.length; i++)
                threads[i] = new Thread(new MyRunnable());
            MyRunnable.threads = threads;
            for (int i = 0; i < threads.length; i++)
                threads[i].start();
            for (int i = 0; i < threads.length; i++) {
                try {
                    threads[i].join();
                } catch (InterruptedException ex) {
                    Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
                }
            }
            Date d2 = new Date();
            System.out.println("" + numberOfThreads + " Thread(s): " + (d2.getTime() - d1.getTime()) + "ms.");
            MyRunnable.counter = null;
            MyRunnable.numberOfThreads = 0;
            MyRunnable.threads = null;
        }
    }

    private static class MyRunnable implements Runnable {

        public static AtomicInteger counter = null;
        public static int numberOfThreads = 0;
        public static Thread[] threads = null;

        @Override
        public void run() {

            for (int i = 0; i < 1000000; i++) {

                int k = 1;
                for (int j = 0; j < 1000000 / numberOfThreads; j++)
                    k *= j;

                if (counter.decrementAndGet() == 0) {

                    counter.set(numberOfThreads);

                    for (int j = 0; j < threads.length; j++)
                        threads[j].interrupt();
                }

                while (!Thread.interrupted()) {}
            }
        }
    }
}