import java.io.*;

class RWLock 
{
 private int lockVal;

 public RWLock( int pVal)
   {
    lockVal = pVal;
   }

 public RWLock ()
   {
    lockVal = 0;
   }

 public RWLock(RWLock pt)
   {
    lockVal = pt.getLockVal();
   }

 public int getLockVal ()
   {
    return lockVal;
   }

 public String toString()
   {
    String str =  "lockVal: " + lockVal;
    return str;
   }

 public synchronized boolean setReadLock()
   {
    if (lockVal < 0)
       return false;
    else
      {
       lockVal++;
       return true;
      }
   }

 public synchronized boolean clearReadLock()
   {
    if (lockVal <= 0)
       return false;
    else
      {
       lockVal--;
       return true;
      }
   }

 public synchronized boolean setWriteLock()
   {
    if (lockVal != 0)
       return false;
    else
      {
       lockVal = -1;
       return true;
      }
   }

 public synchronized boolean clearWriteLock()
   {
    if (lockVal != -1)
       return false;
    else
      {
       lockVal = 0;
       return true;
      }
   }

 public static void main (String[] args)
   {
    RWLock rwl1 = new RWLock ();
    System.out.println ("rwl1 = " + rwl1);

    System.out.print ("Setting read lock on rwl1: ");
    if (rwl1.setReadLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.print ("Setting write lock on rwl1: ");
    if (rwl1.setWriteLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.print ("Setting read lock on rwl1: ");
    if (rwl1.setReadLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.print ("Clearing read lock on rwl1: ");
    if (rwl1.clearReadLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.print ("Clearing write lock on rwl1: ");
    if (rwl1.clearWriteLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.print ("Clearing read lock on rwl1: ");
    if (rwl1.clearReadLock())
        System.out.println ("success rwl1 = " + rwl1);
    else
        System.out.println ("fail rwl1 = " + rwl1);

    System.out.println ();
    RWLock rwl2 = new RWLock ();
    System.out.println ("rwl2 = " + rwl2);

    System.out.print ("Setting write lock on rwl2: ");
    if (rwl2.setWriteLock())
        System.out.println ("success rwl2 = " + rwl2);
    else
        System.out.println ("fail rwl2 = " + rwl2);

    System.out.print ("Setting read lock on rwl2: ");
    if (rwl2.setReadLock())
        System.out.println ("success rwl2 = " + rwl2);
    else
        System.out.println ("fail rwl2 = " + rwl2);

    System.out.print ("Setting write lock on rwl2: ");
    if (rwl2.setWriteLock())
        System.out.println ("success rwl2 = " + rwl2);
    else
        System.out.println ("fail rwl2 = " + rwl2);

    System.out.print ("Clearing write lock on rwl2: ");
    if (rwl2.clearWriteLock())
        System.out.println ("success rwl2 = " + rwl2);
    else
        System.out.println ("fail rwl2 = " + rwl2);

    System.out.print ("Clearing read lock on rwl2: ");
    if (rwl2.clearReadLock())
        System.out.println ("success rwl2 = " + rwl2);
    else
        System.out.println ("fail rwl2 = " + rwl2);

   }
}