class Node {
    private Object item;
    private Node firstChild;
    private Node lastChild;
    private Node nextSibling;

    public Node(Object item) {
	this.item = item;
	firstChild = null;
	lastChild = null;
	nextSibling = null;
    }
    public void addChild(Node n) {
	if (firstChild == null)
	    firstChild = n;
	if (lastChild != null)
	    lastChild.nextSibling = n;
	lastChild = n;
    }
    private void visit() {
	System.out.print(item + " ");
    }
    public void preorder() {
	visit();
	for (Node n = firstChild; n != null; n = n.nextSibling)
	    n.preorder();
    }
    public void postorder() {
	for (Node n = firstChild; n != null; n = n.nextSibling)
	    n.postorder();
	visit();
    }
    public int size() {
	int size = 1;
	for (Node n = firstChild; n != null; n = n.nextSibling)
	    size += n.size();
	return size;
    }
    public int height() {
	int height = -1;
	for (Node n = firstChild; n != null; n = n.nextSibling)
	    if (n.height() > height)
		height = n.height();
	return height + 1;
    }
}

class Tree {
    public static Node makeTree() {
	Node root = new Node("root");
	Node student = new Node("student");
	root.addChild(student);
	Node name = new Node("name");
	Node address = new Node("address");
	Node major = new Node("major");
	student.addChild(name);
	student.addChild(address);
	student.addChild(major);
	name.addChild(new Node("Bill White"));
	address.addChild(new Node("300 West 721 North Provo, UT 84604"));
	major.addChild(new Node("Computer Science"));
	return root;
    }

    public static Node buildTree() {
	Node a = new Node("A");
	Node b = new Node("B");
	Node c = new Node("C");
	Node d = new Node("D");
	Node e = new Node("E");
	Node f = new Node("F");
	Node g = new Node("G");
	Node h = new Node("H");
	Node i = new Node("I");
	Node j = new Node("J");
	Node k = new Node("K");
	
	a.addChild( b );
	a.addChild( c );
	a.addChild( d );
	a.addChild( e );
	b.addChild( f );
	b.addChild( g );
	d.addChild( h );
	e.addChild( i );
	e.addChild( j );
	j.addChild( k );
	
	return a;
    }

    public static void main(String[] args) {
	//	Node tree = makeTree();
	Node tree = buildTree();
	System.out.println("Preorder");
	tree.preorder();
	System.out.println();
	System.out.println("Postorder");
	tree.postorder();
	System.out.println();
	System.out.println("size " + tree.size());
	System.out.println("height " + tree.height());
    }
}