import java.io.Reader;
import java.util.Scanner;
import java.util.concurrent.ConcurrentHashMap;

public class Relay {
    private Integer nextId;
    private Integer currentId;
    private ConcurrentHashMap<Thread,Integer> idMap;
    private Scanner data;
    private Thread T;
    private boolean koniec;
    private boolean start;

    public synchronized void inform(){
        notifyAll();
    }

    public Relay(Reader reader) {
        data=new Scanner(reader);
        idMap=new ConcurrentHashMap<Thread,Integer>();
        T= new Thread(){
            public void run(){
                while(data.hasNextInt()){
                    synchronized (Relay.this){
                         if(nextId==null) {
                                nextId = data.nextInt();
                                inform();
                        }
                        try {
                            wait();
                        }
                        catch (InterruptedException e) {
                        }
                    }
                }
                koniec=true;
                inform();
            }
        };
        T.start();

    }


    public synchronized void register(int id, Thread competitor) {
        idMap.put(competitor,id);
    }

    public synchronized void startRelayRace() {
        start=true;
        inform();
    }

    public synchronized boolean dispatch() {
        if(koniec && nextId==null && currentId==null) {
            try {
                return false;
            }
            finally {
                inform();
            }
        }

        while(!start){
            try{
                wait();
            } catch (InterruptedException e) {
            }
        }


        if(idMap.get(Thread.currentThread()).equals(currentId) ){
            currentId=null;
            inform();
        }

        while(currentId!=null || !idMap.get(Thread.currentThread()).equals(nextId) ){
            try {
                if(koniec && nextId==null && currentId==null) {
                    try {
                        return false;
                    }
                    finally {
                        inform();
                    }
                }
                wait();

            } catch (InterruptedException e) {}
        }


        currentId=nextId;
        nextId=null;
        inform();
        return true;
    }
}