using System;

using System.Linq;

​

public class Program

{

    private Random r = new Random();

    private string numbers = "0123456789";

    private string words = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

    public static void Main()

    {   

        var key = GetFirstSection() + "-" + GetSecondSection() + "-";       

    }

    private string GetFirstSection()

    {

        return GetRandomNumber() + GetRandomWord() + GetRandomNumber() + GetRandomWord();       

    }

    private string GetSecondSection()

    {

        var section = "";

        var word = GetRandomWord();

        var doubleWord = word + word;

        if(r.Next(2))   

    }

    private string GetRandomNumber() => numbers[r.Next(numbers.Length)].ToString();

    private string GetRandomWord() => words[r.Next(words.Length)].ToString();

}