import java.util.LinkedList;
public class Simulation {

    LinkedList list;
    State s;
    double time;
    double runTime;

    public Simulation() {
    	list=new LinkedList();
    	s=new State();
    	time=0;
    	runTime=1000;
    	list.add(new Event ("Arrival",getNextTime()));
    	list.add(new Event("Stop",runTime));
    	simulate();
    	
    }
    public int getNextTime(){
    	return 2;
    }
    public void simulate(){
    	boolean end=false;
    	while(!end){
    		Event e=(Event)list.remove();
    		if(e.type=="Arrival")
    			arrival(e);
    		else if(e.type.equals("Departure"))
    			departure(e);
    		else
    			end=true;
    		System.out.println(time+"->"+new State().QL);	
    	}
	
    }
    public void arrival(Event e){
    	if(new State().status==0){
    		new State().status=1;
    		list.add(new Event("Departure",time+this.getNextTime()));
    	}
    	else	
    		new State().QL++;
    	list.add(new Event("Arrival",time+this.getNextTime()));
    }
    public void departure(Event e){
    	if(new State().QL>0){
    		new State().QL--;
    		new State().status=1;
    		list.add(new Event("Departure",time+this.getNextTime()));
    	}
    	else
    		new State().status=0;	
    }
    public static void main(String []arg){
    	new Simulation();
    }
}

class State{
	int QL;
	int status;
	public State(){
		QL=0;
		status=0;
	}
}
class Event{
	String type;
	double time;
	public Event(String ty, double t){
		type=ty;
		time=t;
	}
}