using System;

public class Program

{

     public class TreeNode 

     {

         public int val;

         public TreeNode left;

         public TreeNode right;

         public TreeNode(int val, TreeNode left = null, TreeNode right = null) 

         {

             this.val = val;

             this.left = left;

             this.right = right;

         }

     }

    public static TreeNode TrimBST(TreeNode root, int low, int high) 

    {

        if (root == null)

        {

            return root;

        }

        if(root.val < low)

        {

            return TrimBST(root.right, low, high);

        }

        else if(root.val > high)

        {

            return TrimBST(root.left, low, high);

        }

        root.left = TrimBST(root.left, low, high);

        root.right = TrimBST(root.right, low, high);  

        return root;

    }

    public static void Main()

    {

        Console.WriteLine("UniLecs");

        var root = new TreeNode(3);

        root.left = new TreeNode(0);

        root.right = new TreeNode(4);

        root.left.right = new TreeNode(2);

        root.left.right.left = new TreeNode(1);

        var trimRoot = TrimBST(root, 1, 3);

        Console.WriteLine(trimRoot.val);

        Console.WriteLine(trimRoot.left.val);

        Console.WriteLine(trimRoot.left.left.val);

    }

}