public class Node { 
    private Node left;               // (1)
    private int data;                // (2)
    private Node right;              // (3)
    
    //
    // A Node in a BTree has a left field (1) which is a 
    // Node or empty (null). It contains an integer valued data (2)
    // and has a right field (3) again a Node or empty (null).
    //

    public Node(){
	left = null;
	data = Integer.MIN_VALUE;
	right = null;
    }
    //
    // Default constructor. Left and right are null
    // and data has the smallest integer value.
    //

    public Node(int data){
	left = null;
	this.data = data;
	right = null;
    }
    //
    // Construct a leaf node, with empty left and right
    //

    public Node(Node left,int data,Node right){
	this.left = left;
	this.data = data;
	this.right = right;
    }
    //
    // Construct a new Node with a specified left,
    // data, and right.
    //

    public Node getLeft(){return left;}
    public int getData(){return data;}
    public Node getRight(){return right;}
    //
    // The 3 accessor methods for a Node
    //
    
    public void setLeft(Node l){left = l;}
    public void setData(int i){data = i;}
    public void setRight(Node r){right = r;}
    //
    // The 3 update methods for a node
    //

    public String toString(){return "" + data;}
    //
    // For printing a Node. It just converts its data
    // to a string
    //

    public boolean isLeaf(){return left==null && right==null;}
    //
    // A Node is a leaf if its left and right are empty
    //

}