using System;

using System.Linq;

using System.Collections.Generic;

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 List<int> RightSideView(TreeNode root) {

        var result = new List<int>();

        if (root == null) 

            return result;

        TreeNode curr = null;

        var level = new Queue<TreeNode>();

        level.Enqueue(root);

        while (level.Any())

        {

            int levelSize = level.Count;

            for (int i = 0; i < levelSize; i++)

            {

                curr = level.Dequeue();

​

                if (i == 0)

                    result.Add(curr.val);

​

                if (curr.right != null)

                    level.Enqueue(curr.right);

​

                if (curr.left != null)

                    level.Enqueue(curr.left);

            }

        }

        return result;

    }

    public static void Main()

    {

        Console.WriteLine("UniLecs");

        // tests

        var root = new TreeNode(1);

        root.left = new TreeNode(2);

        root.right = new TreeNode(3);

        root.left.right = new TreeNode(5);

        Console.WriteLine(string.Join(" ", RightSideView(root))); // 1 3 5

    }

}