public void randomWalk()
   {
      for (int counter = 0; counter < 100; counter++)

      if( randomInteger()==1 )
      {
         right();

      }
      else

      if( randomInteger()==2 )

      {
         left();

      }

      else

      if( randomInteger()==3 )

      {

         up();

     }

      else

      if( randomInteger()==4 )

      {
         down();

      }

      else
   }