using System;

public class Program

{

    public static void Main()

    {

        bool b = checkValue("01, FF, 3E, 27, 7F");      // textBlock.Text

        Console.WriteLine(b);

    }

        static bool checkValue(string s)

        {

            string[] tab = s.Split(new string[] { ", " }, StringSplitOptions.None ); // split string with ", " as a delimiter

            foreach (var hex in tab)

            {

                if (hex.Length != 2) // Check if we have two item

                    return false;

                foreach(var c in hex)

                {

                    // check for valid letter (upper and lower) and digit

                    if(!((c >= '0' && c <= '9') || 

                        (c >= 'a' && c <= 'f') || 

                        (c >= 'A' && c <= 'F')))

                    return false;

                }

            }

            return true;

        }

}