using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Starting...");

        var symbols = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".ToCharArray().ToList().ToDictionary(c => c, c => 0);

        var guids = CreateGuids(10000);

        foreach (var item in guids)

        {

            AnalyzeGuid(item, symbols);

        }

​

        var ordered = symbols.OrderByDescending(d => d.Value).Take(5);

        Console.WriteLine("Results:\n");

        var rank = 0;

        foreach (var item in ordered)

        {

            Console.WriteLine("Rank: " + (++rank) + " - Letter: " + (item.Key.ToString()) + " - Count: " + (item.Value));

        }

​

        Console.ReadLine();

    }

​

    static List<string> CreateGuids(int amount)

    {

        var guids = new List<string>(amount);

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

        {

            guids.Add(Guid.NewGuid().ToString().ToUpper().Replace("-", ""));

        }

​

        return guids;

    }

​

    static void AnalyzeGuid(string guid, Dictionary<char, int> collection)

    {

        var chars = guid.ToCharArray();

        for (int i = 0; i < chars.Length; i++)

        {

            if (collection.ContainsKey(chars[i]))

            {

                collection[chars[i]]++;

            }

        }

    }

}