import java.util.concurrent.*;


/** Start >java VrangLaas <ant traader>
Viser at synkronisering i ulike rekkef?lger (ikke sortert) g?r galt'*/

public class VrangLaas{
	int  a=0,b=0;               // Felles variable a,b
	int antGanger;
	Semaphore ferdig, vent ;
	SkrivA aObj;
    SkrivB bObj;

	public static void main (String [] args) {
		if (args.length != 1) {
			System.out.println(" bruk: java VranLaas <ant ganger oeke> ");
		  } else {
			 int antKjerner = Runtime.getRuntime().availableProcessors();
			 System.out.println("Maskinen har "+ antKjerner + " prosessorkjerner.\n");
			 VrangLaas p =  new VrangLaas();
			 p.antGanger  = Integer.parseInt(args[0]);
			 p.utfor();
		 }
	} // end main

	void  utfor () {
	    vent   = new Semaphore(1); // vent mellom algoritmer og tidtaging
        ferdig = new Semaphore(1);
		(aObj =  new SkrivA()).start();
		(bObj =  new SkrivB()).start();
	 } // utfor

	 class SkrivA extends Thread{

	       public void run() {
			   for (int j = 0; j<antGanger; j++) {
			       try {  // wait on the other thread
					  ferdig.acquire();
					  vent.acquire();
			        } catch (Exception e) {return;}

			          a++;
		              System.out.println("a="+a);
                   vent.release();
				  ferdig.release();
			  }
			} // end run A
     } // end class SkrivA

      class SkrivB extends Thread{

		   public void run() {
			   for (int j = 0; j<antGanger; j++) {
				   try {  // wait on the other thread
					  vent.acquire();
					  ferdig.acquire();
	         	   } catch (Exception e) {return;}
				       b++;
		              System.out.println("b="+b);
				  vent.release();
				  ferdig.release();
			  } // end for
			} // end run B
     } // end class SkrivB


}// END class Parallell