content: /* Class containing left and right child of current 
     node and key value*/
  class Node 
  { 
      int key; 
      Node left, right; 
    
      public Node(int item) 
      { 
          key = item; 
          left = right = null; 
      } 
  } 
    
  // A Java program to make Binary Tree 
  class BinaryTree 
  { 
      // Root of Binary Tree 
      Node root; 
    
      // Constructors 
      BinaryTree(int key) 
      { 
          root = new Node(key); 
      } 
    
      BinaryTree() 
      { 
          root = null; 
      } 
    
      public static void main(String[] args) 
      { 
          BinaryTree tree = new BinaryTree(); 
    
          /*create root*/
          tree.root = new Node(1); 
    
          /* following is the tree after above statement 
    
                1 
              /   \ 
            null  null     */
    
          tree.root.left = new Node(2); 
          tree.root.right = new Node(3); 
    
          /* 2 and 3 become left and right children of 1 
                 1 
               /   \ 
              2      3 
            /    \    /  \ 
          null null null null  */
    
    
          tree.root.left.left = new Node(4); 
          /* 4 becomes left child of 2 
                      1 
                  /       \ 
                 2          3 
               /   \       /  \ 
              4    null  null  null 
             /   \ 
            null null 
           */
      } 
  } 
  