static void Main(string[] args)
        {
            WriteLine("Calculate Height of a Tree in O(log n) time");
            WriteLine();

            WriteLine("Inserted Nodes: 20, 30, 10, 40, 60, 5");

            BST root = null;

            BST bst = new BST();

            root = bst.Insert(root, 20);
            root = bst.Insert(root, 30);
            root = bst.Insert(root, 10);
            root = bst.Insert(root, 40);
            root = bst.Insert(root, 60);
            root = bst.Insert(root, 5);

            WriteLine();
            WriteLine();

            WriteLine($"Height of a Tree is: {bst.Height(root)}");
            WriteLine();
        }
 public BST(int _data)
 {
     this.data = _data;
     this.left = this.right = null;
 }