import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import javax.swing.text.AbstractDocument.LeafElement;

class BinaryNode {
    
    
    private Comparable value;    
    
    
    private BinaryNode left;         
    private BinaryNode right;        
    
   
   
    public BinaryNode(Comparable value) {
        this.value = value;
        this.left = null; 
        this.right = null;
    }

    
    public Comparable getValue() {
        return value;
    }

    public void setValue(Comparable value) {
        this.value = value;
    }

    
    
 
    public BinaryNode getLeft() {
        return left;
    }
 
    
    public void setLeft(BinaryNode left) {
        this.left = left;
    }

  
    public BinaryNode getRight() {
        return right;
    }

    
    /**
     * 
     * Set the right subtree
     * 
     * @param right the right subtree
     */
    public void setRight(BinaryNode right) {
        this.right = right;
    }    
}

public class BinaryTree {
    private BinaryNode root;
    
   
    public BinaryTree() {
        root = null;
    }
    
   
    public void add(Comparable value) {
        root = add(value, root);
    }
    
    private BinaryNode add(Comparable v, BinaryNode n) {
        //check if real value
        if(n == null ) {
            //create a new node
            n = new BinaryNode(v);
        }
        else if(v.compareTo(n.getValue()) < v.compareTo(v)){
            n.setLeft(add(v, n.getLeft()));
        }
        else if(v.compareTo(n.getValue()) > v.compareTo(v)) {
            n.setRight(add(v, n.getRight()));
        }
        else {
            throw new RuntimeException("Duplicate value:"+v);
        }
        return n;
    }
    
    private void printInOrder() {
        if (root != null) {
            printInOrder(root);
        }
    }
    public boolean isEmpty( ) {
        return root == null;
    }
    
    
    private void printInOrder(BinaryNode n) {
        if (n != null) {            
            //left
            printInOrder(n.getLeft());
            
            //current
            System.out.println(n.getValue());
            //right
            printInOrder(n.getRight());
            
        }
    }
    
    
    public static void main( String  args ) {
        BinaryTree t = new BinaryTree( );
        
        t.add("aaa");
        t.add("uuu");
        t.add("yyy");
        t.add("bbb");
        
       
       
        
        t.printInOrder();
    }
}

else {            throw new RuntimeException("Duplicate value:"+v);        }

        else if(v.compareTo(n.getValue()) < v.compareTo(v)){