using System;

using System.Collections.Concurrent;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        for (int step = 1; step <= 10; step++)

        {

            Random random = new(0);

            Console.WriteLine($"Step: {step}");

            int[] source = Enumerable.Range(1, 15)

                .OrderBy(_ => random.Next())

                .Select(x => x * step)

                .ToArray();

            Console.WriteLine($"Source shuffled: [{String.Join(", ", source)}]");

            Console.WriteLine($"Source ordered:  [{String.Join(", ", source.Order())}]");

            ConcurrentDictionary<int, string> dictionary = new();

            foreach (int i in source) dictionary.TryAdd(i, null);

            Console.WriteLine($"dictionary.Keys: [{String.Join(", ", dictionary.Keys)}]");

            Console.WriteLine();

        }

    }

}