using System;

using System.Collections.Generic;

public class Program

{

    private static readonly IReadOnlyList<Difficulty> Choices = new List<Difficulty>

    {

        Difficulty.Easy,

        Difficulty.Med,

        Difficulty.Hard

    };

    private enum Difficulty 

    { 

        Easy = 1,

        Med = 2,

        Hard = 4,

        Any = Easy | Med | Hard,

    };

    public static void Main()

    {

        Random rnd = new Random();

        Difficulty range = Difficulty.Any;

        Console.WriteLine($"Without removed: {range}");

        var random = rnd.Next(0, Choices.Count);

        Console.WriteLine($"Random index: {random}. Value: {Choices[random]}");

        range &= ~Choices[random];

        Console.WriteLine($"With removed: {range}");

        Console.WriteLine($"Has Easy: {range.HasFlag(Difficulty.Easy)}");

        Console.WriteLine($"Has Med: {range.HasFlag(Difficulty.Med)}");

        Console.WriteLine($"Has Hard: {range.HasFlag(Difficulty.Hard)}");

    }

}