class Node {
   public int data;
   public Node nextOne;

   // Constructor
   public Node (int initialValue) {
       data = initialValue;
       nextOne = null;
   }
}

class ListOfInts {

   private Node theList;
   private int numElements;
   // Don't need a maxListSize; no limit other than memory limits.

   // Constructor
   public ListOfInts() {
 	// Actually, the default constructor would do the same inits for us.
        theList = null;
        numElements = 0;
   }

   public void addInt (int n) {
	Node temp = new Node(n);
        temp.nextOne = theList;
        theList = temp;
        numElements++;
   }

   public float average () {
 	Node temp = theList;
        int sum = 0;
	while (temp != null) { 
        // Or could still use this: for (int i=0; i<numElements; i++) {
                sum += temp.data;
		temp = temp.nextOne;
    	}
        return sum / numElements;
   }

   // No different.  But how would it look if we didn't keep a counter?
   // (DO we *need* to?  If not, should we choose to?)
   public int size() {
	return numElements;
   }

   // Always returns false, but not silly to include this.  It's here
   // for backwards compatibility with the earlier version.
   public boolean full() {
  	return false;
   }
}


class Student {

   private int studentNum;
   private String name;
   private ListOfInts markList;

   public Student (int n, String s) {
	studentNum = n;
	name = s;
	markList = new ListOfInts();
   }

   public void passCourse (int mark) {
 	markList.addInt(mark);
   }

   public float average() {
	return markList.average();
   }

}


class Example {

   public static void main (String[] args) {

       	Student Fred, Betty;
	Fred = new Student(12345, "Fred Flintstone");
	Fred.passCourse(75);
	Fred.passCourse(68);

	Betty = new Student(90210, "Betty Rubble");
	Betty.passCourse(92);

	System.out.println("Fred's avg: " + Fred.average() + " and " +
                           "Betty's avg: " + Betty.average());
   }
}