Advanced Topics 11. Count of Letters

// Write a program that reads a list of letters and prints for each letter how many times it appears in the list. The letters should be listed in alphabetical order.

namespace _11.CountOfLetters
{
    using System;

    public class CountOfLetters
    {
        public static void Main(string[] args)
        {
            checked
            {
                Console.WriteLine("Enter your List of letters on single line, separated by a space!");
                string inputLine = Console.ReadLine();

                char[] separators = new char[] { ' ', ',', ';' };
                string[] letters = inputLine.Split(separators, StringSplitOptions.RemoveEmptyEntries);
                if (letters.Length > 0)
                {
                    Array.Sort(letters);
                    int countLetterAppears = 1;
                    for (int i = 1; i < letters.Length; i++)
                    {
                        if (letters[i] == letters[i - 1])
                        {
                            countLetterAppears++;
                        }
                        else
                        {
                            Console.WriteLine("{0} -> {1}", letters[i - 1], countLetterAppears);
                            countLetterAppears = 1;
                        }
                    }

                    Console.WriteLine("{0} -> {1}", letters[letters.Length - 1], countLetterAppears);
                }
                else
                {
                    Console.WriteLine("Error! - Empty List!!!");
                }
            }
        }
    }
}