using System;

using System.Collections.Generic;

using System.Linq;

​

class Program

{

    static void Main()

    {

        Random random = new Random();

        string[] colours = { "Red", "Green", "Blue", "Yellow" };

        int sockCount = random.Next(10, 21);

        List<string> sockDrawer = new List<string>();

​

        for (int i = 0; i < sockCount; i++)

        {

            sockDrawer.Add(colours[random.Next(colours.Length)]);

        }

​

        Console.WriteLine("Socks in the drawer:");

        Console.WriteLine("[ " + string.Join(" ", sockDrawer) + " ]\n");

        Console.WriteLine($"Total socks: {sockCount}\n");

​

        int totalPairs = 0;

​

        foreach (string colour in colours)

        {

            int count = sockDrawer.Count(s => s == colour);

            int pairs = count / 2;

            totalPairs += pairs;

            Console.WriteLine($"{colour}: {count} socks, {pairs} pairs");

        }

​

        Console.WriteLine($"\nTotal pairs: {totalPairs}\n");

        double probability = sockDrawer.Sum(s => (sockDrawer.Count(c => c == s) - 1) / 2.0) / ((sockCount * (sockCount - 1)) / 2.0);

        Console.WriteLine($"Chance of picking a matching pair: {probability:P2}");

    }

}

​