using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string s = "Aman";

        var testresult = CountLetters(s);

        foreach(var t in testresult)

        {

            Console.WriteLine("Letter = {0}\t Count = {1}",t.Key, t.Value);

        }

    }

    public static IDictionary<char, int> CountLetters(string s)

    {

        string lowercase = s.ToLower();

        IDictionary<char, int> result = new Dictionary<char, int>();

        foreach(var c in lowercase)

        {

            if(!result.Any(x=>x.Key == c))

             {

                 result.Add(c, lowercase.Where(x=>x == c).Count());

             }             

        }

        return result;

    }

}