public class InstanceOFTutorial{
	
   static String count(ArrayList mylist){
      int a = 0,b = 0,c = 0;
      for(int i = 0; i < mylist.size(); i++){
         Object element=mylist.get(i);
         if( element instanceof Student)
            a++;
         if( element instanceof Rockstar)
            b++;
         if( element instanceof Hacker)
            c++;
      }
      String ret = Integer.toString(a)+" "+ Integer.toString(b)+" "+ Integer.toString(c);
      return ret;
   }