using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var name = "Riahna asasff";

            var a = name.Select(n=>n.ToString()).ToArray(); 

            var b = new string(name.Reverse().ToArray()).Select(n=>n.ToString()).ToArray(); 

           var c = a.Zip(b, (first, second) => first + "" + second);

​

​

        Console.WriteLine(string.Join("", c));

    }

}