using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        PrintCharsAndFrequencies("aaabbbbcccdddd");

    }

    public static string PrintCharsAndFrequencies(string s)

    {

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

​

        // make char array from input

        char[] chars = s.ToCharArray();

​

        // add characters to dictionary so we can count them

        foreach (char c in chars)

        {

            if (!charFrequency.ContainsKey(c))

            {

                charFrequency.Add(c, 1);

            }

            else

            {

                charFrequency[c] = charFrequency[c] + 1;

            }

        }

​

        var results = new List<string>();

​

        // format string from key value pairs that corespond to character frequency pairs

        foreach (KeyValuePair<char, int> kvp in charFrequency.OrderBy(x => x.Key))

        {

            results.Add(string.Format("{0}{1}", kvp.Key, kvp.Value));

        }

​

        string formatedResults = String.Join(" ", results);

​

        // print results

        Console.Write(formatedResults);

​

        // return formated string for test comparison

        return formatedResults;

    }

}