using System;
using System.Collections.Generic;

public class Test
{
	public static void Main()
	{
		var root = new TreeNode<int, string>(8, "Value-8");
		root.Left = new TreeNode<int, string>(4, "Value-4");
		root.Left.Left = new TreeNode<int, string>(2, "Value-2");
		root.Left.Left.Left = new TreeNode<int, string>(1, "Value-1");
		root.Left.Left.Right = new TreeNode<int, string>(3, "Value-3");
		root.Left.Right = new TreeNode<int, string>(6, "Value-6");
		root.Left.Right.Left = new TreeNode<int, string>(5, "Value-5");
		root.Left.Right.Right = new TreeNode<int, string>(7, "Value-7");
		root.Right = new TreeNode<int, string>(12, "Value-12");
		root.Right.Left = new TreeNode<int, string>(10, "Value-10");
		root.Right.Left.Left = new TreeNode<int, string>(9, "Value-9");
		root.Right.Left.Right = new TreeNode<int, string>(11, "Value-11");
		root.Right.Right = new TreeNode<int, string>(14, "Value-14");
		root.Right.Right.Left = new TreeNode<int, string>(13, "Value-13");
		root.Right.Right.Right = new TreeNode<int, string>(15, "Value-15");
		
		foreach (var item in root.TraverseLevelOrder())
			Console.WriteLine(item.Value);
	}
	
	
}

public class TreeNode<TKey, TValue>
{
	public TreeNode(TKey key, TValue value)
	{
		this.Key = key;
		this.Value = value;
	}
	
	public TKey Key { get; private set; }
	
	public TValue Value { get; set; }
	
	public TreeNode<TKey, TValue> Left { get; set; }
	
	public TreeNode<TKey, TValue> Right { get; set; }
	
	public IEnumerable<TreeNode<TKey, TValue>> TraverseInOrder()
	{
		if (this.Left != null)
			foreach (var item in this.Left.TraverseInOrder())
				yield return item;
				
		yield return this;
		
		if (this.Right != null)
			foreach (var item in this.Right.TraverseInOrder())
				yield return item;
	}
	
	public IEnumerable<TreeNode<TKey, TValue>> TraverseLevelOrder()
	{
		var queue = new Queue<TreeNode<TKey, TValue>>();
		queue.Enqueue(this);
		
		while (queue.Count > 0)
		{
			var node = queue.Dequeue();
			yield return node;
			
			if (node.Left != null)
				queue.Enqueue(node.Left);
				
			if (node.Right != null)
				queue.Enqueue(node.Right);
		}
	}
}