import java.util.concurrent.Semaphore;

public class vehicle implements Runnable
{
    static int numCars=0;

    private int carNum;
    private boolean north;
    private boolean crossed= false;
    static Semaphore mutex;

public vehicle(boolean isNorth)
{
    north=isNorth;
    numCars=numCars+1;
    carNum=numCars;


    mutex=new Semaphore(1);

}

public void run()
{
    System.out.println("car number: "+carNum+" has arrived at bridge.");
    crossBridge();                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  )
}

public void setCrossed()
{
    crossed=true;
}


public int getNumber()
{
    return carNum;
}




public Boolean crossBridge()
{

    try
    {
        mutex.acquire();
    }
    catch(InterruptedException e)
    {System.out.println("mutex failed to acquire.");}

    setCrossed();
    mutex.release();
    System.out.println("car number "+carNum+" has crossed the bridge.");
    return true;
}



}