import java.util.Date;
import java.util.Random;

public class SemaSk8r {
    // Maximum zambonification time (ms)
    private static final int MAXZAMBONIFICATIONTIME = 3000;
    // Maximum time between using the Zambony (ms)
    private static final int MAXBETWEENZAMBONIFICATIONTIME = 10000;
    // Maximum time between skater creation (ms)
    private static final int MAXBETWEENNEWSKATERTIME = 10000;
    // Maximum skate time (ms)
    public static final int MAXSKATETIME = 15000;
    // Maximum number of simultaneous skaters
    private static final int MAXSKATERS = 4;
    
    private int sk8rCt = 0;
    private boolean isZambonying = false;
    private Random rndGen = new Random(new Date().getTime());

    public void go() {
        Zamboni z = new Zamboni();
        new Thread(z, "Zamboni").start();

        int i = 0;
        while (true) {
            new Thread(new Sk8r(), "S" + i++).start();
            try {
                Thread.sleep(rndGen.nextInt(MAXBETWEENNEWSKATERTIME));
            } catch (InterruptedException e) {
            }
        }
    }

    public static void main(String[] args) {
        new SemaSk8r().go();
    }

    class Zamboni implements Runnable {

        @Override
        public void run() {
            while (true) {
                System.out.println("Ready to Zambonify");
                System.out.println("Start Zambonifying");
                isZambonying = true;
                areSk8rsOK();
                try { // Zambonifying
                    Thread.sleep(rndGen
                            .nextInt(MAXZAMBONIFICATIONTIME));
                } catch (InterruptedException e) {
                }
                isZambonying = false;
                System.out.println("Done Zambonifying");
                try {
                    Thread.sleep(rndGen
                            .nextInt(MAXBETWEENZAMBONIFICATIONTIME));
                } catch (InterruptedException e) {
                }
            }
        }
    }

    class Sk8r implements Runnable {

        @Override
        public void run() {
            System.out.println(Thread.currentThread() + ": Ready to skate");
            System.out.println(Thread.currentThread() + ": Start skating");
            sk8rCt++;
            areSk8rsOK();
            try { // Skating
                Thread.sleep(rndGen.nextInt(MAXSKATETIME));
            } catch (InterruptedException e) {
            }
            System.out.println(Thread.currentThread() + ": Done skating");
            sk8rCt--;
        }
    }

    public int getNoSk8rs() {
        return sk8rCt;
    }

    public void areSk8rsOK() {
        if (getNoSk8rs() > MAXSKATERS) {
            System.err.println("HEADLINE: Overcrowding at rink kills " + getNoSk8rs() + " skaters.");
            System.exit(1);
        }
        if (isZambonying && getNoSk8rs() > 0) {
            System.err.println("HEADLINE:  " + getNoSk8rs()
                    + " skaters killed in grizzly zamboni accident");
            System.exit(1);
        }
    }
}