/* A program illustrating binary trees and recursion.
   Creates and print horizontally the following tree:

             root
        ______|_______
       |              |
     node1          node4
    ___|___           |
   |       |          |
 node2   node3      node5
                  ___|___
                 |       |
               node6   node7

*/


class Node {

   public Object data;
   public Node left;
   public Node right;

   public Node (Object d, Node l, Node r) {

      data = d;
      left = l;
      right = r;
   }

   public void ptree (Node t, int pos) {

     if (t != null) {
        tab (pos);
        System.out.println (t.data);
        ptree (t.left, pos+1);
        ptree (t.right, pos+1);
     }
   }

   private void tab (int n) {

     for (int i=0; i<n; i++) System.out.print("  ");

   }

}


class Tree {

  public static void main (String[] args) {

     Node root = new Node("root", 
                          new Node("node1",
                                   new Node("node2",null,null),
                                   new Node("node3",null,null) 
                                  ),
                          new Node("node4",
                                   new Node("node5",
                                            new Node("node6",null,null),
                                            new Node("node7",null,null) 
                                           ),
                                   null) 
                         );

     root.ptree(root, 0);
  }


}