using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public class Node

    {

        public int Value { get; set; }

        public Node Left { get; set; }

        public Node Right { get; set; }

        public Node (int value)

        {

            Value = value;

        }

    }

    public static void Main()

    {

        var root = new Node(5)

        {

            Left = new Node(3)

            {

                Left = new Node(2)

                {

                    Left = new Node(6)  

                },

                Right = new Node(8)

            },

            Right = new Node(4)

            {

                Left = new Node(1)

                {

                    Left = new Node(3)

                    {

                        Left = new Node(3)  

                    }

                },

                Right = new Node(1)

            }

        };

        var stack = new Stack<Node>();

        stack.Push(root);

        Recurse(stack);

    }

    public static void Recurse(Stack<Node> stack)

    {

        while (stack.Count > 0)

        {

            var current = stack.Pop();

            Console.WriteLine(current.Value);

            if (current.Left != null)

            {

                stack.Push(current.Left);

                Recurse(stack);

            }

            if (current.Right != null)

            {

                stack.Push(current.Right);

                Recurse(stack);

            }

        }

    }

}