class ListItem {

    Integer data;
    ListItem next;

}


public class OurSortedLinkedList {

    ListItem front = null;
    ListItem rear = null;

    int numItems = 0;


    public void add (Integer K)
    {
	if (front == null) {
	    front = new ListItem ();
	    front.data = K;
	    rear = front;
	    rear.next = null;
	}
	else {
            // This part is a little more complicated now since
            // we have to first find the right place and then
            // possibly insert between existing elements.

	    // Find the right place for it.
	    ListItem listPtr = front;
	    ListItem followPtr = null;
	    while ( (listPtr != null) && (listPtr.data < K) ) {
		followPtr = listPtr;
		listPtr = listPtr.next;
	    }

            // Make the node.
            ListItem nextOne = new ListItem ();
	    nextOne.data = K;

            // There are three cases to handle.
	    if (listPtr == front) {
		// CASE 1: Insert in front.
		nextOne.next = front;
		front = nextOne;
	    }
	    else if (listPtr == null) {
		// CASE 2: Insert at rear.
		rear.next = nextOne;
		rear = nextOne;
	    }
	    else {
            	// CASE 3: Insert in the middle.
		followPtr.next = nextOne;
		nextOne.next = listPtr;
	    }
	}    

	numItems ++;
    }


    public int size ()
    {
	return numItems;
    }

    
    public boolean contains (Integer K)
    {
	if (front == null) {
	    return false;
	}

        // Start from the front and walk down the list. We don't
        // have to go further once we've hit something larger than K.

	ListItem listPtr = front;
	while ( (listPtr != null) && (listPtr.data <= K) ) {
	    if ( listPtr.data.equals(K) ) {
		return true;
	    }
	    listPtr = listPtr.next;
	}
	return false;
    }


    public String toString ()
    {
	if (front == null) {
	    return "empty";
	}

        // Put all the elements (data only) into the string.
	String s = "[";
	ListItem listPtr = front;
	while (listPtr != null) {
	    s += " \"" + listPtr.data + "\"";
	    listPtr = listPtr.next;
	}
	return s + "]";
    }


    public void printWithAddresses ()
    {
	if (front == null) {
	    return;
	}

	ListItem listPtr = front;
	while (listPtr != null) {
            //  listPtr's default toString() prints out the memory address.
	    System.out.println (" \"" + listPtr.data + "\"  at address " + listPtr);
	    listPtr = listPtr.next;
	}
    }


    public static void main (String[] argv)
    {
	OurSortedLinkedList list = new OurSortedLinkedList();
	list.add (3);
	list.add (1);
	list.add (2);
	list.add (4);
	System.out.println (list);
	System.out.println ("2 in list? " + list.contains(2));
	System.out.println ("5 in list? " + list.contains(5));
    }
    

}