using System;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        string userInputString;

        Console.WriteLine("Please enter your string:");

        userInputString = Console.ReadLine().ToUpper(); // To make it case independant as per the requirement

        Console.WriteLine("\n");

        // Not checking for null strings or strings with non-alphabets as they will produce counts as 0 as desired.

        Dictionary <char, int> CountOfAlphabets = new Dictionary <char, int> (); 

        // Using int for storing counts assuming the input string will be of reasonable length

​

        // Adding all alphabets as keys as we will be displaying all the alphabets even if there are not in the string. 

        // This will also provide presorted keys for displaying tabulate later  

        createAlphabetDictionary( ref CountOfAlphabets);

        int totalLettersCounted = CountAlphabetsAndReturnTotalValidLetters(userInputString, ref CountOfAlphabets);

        // Not adhereing to Single Responsibility principle for simplicity here

​

        // use false for keys and true for values

        DisplayTabulate(false , ref CountOfAlphabets); // For Keys 

        DisplayTabulate(true , ref CountOfAlphabets); // For Values

        Console.WriteLine("\n The text has been processed. Total letters counted: [{0}] " , totalLettersCounted);

    }

    public static void createAlphabetDictionary (ref Dictionary <char, int> CountOfAlphabets)

    {

        for(char c = 'A'; c <= 'Z'; c++) 

        {

            char keyOfAlphabet = c;

            CountOfAlphabets.Add(keyOfAlphabet, 0);

        }

    }

    public static int CountAlphabetsAndReturnTotalValidLetters(string _userInputString, ref Dictionary <char, int> CountOfAlphabets)    

    {       

        int _totalLettersCounted = 0;

        foreach (char i in _userInputString)

        {   

            if (CountOfAlphabets.ContainsKey(i)) // Special characters and digits will automatically be ignored

            {

                int currentCount = 0;

                CountOfAlphabets.TryGetValue(i, out currentCount);

                CountOfAlphabets[i] = currentCount + 1; 

                _totalLettersCounted++; // A counter for our final message

            }

        }

        return _totalLettersCounted;

    }

    public static void DisplayTabulate (bool isValue, ref Dictionary <char, int> CountOfAlphabets)

    {

            foreach (var a in CountOfAlphabets)

            {

                if (isValue)

                    Console.Write (a.Value);

                else

                    Console.Write (a.Key);

​

                Console.Write ("|");

            }

            Console.WriteLine ("\n____________________________________________________");    

    }

}