using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

public class Solution

{

    static string shortenString(string input) {

        var word = new List<char>();

        var processedChars = new List<char>();

        foreach(char c in input)

        {

            if(isLetter(c))

            {

                word.Add(c);

            }

            else

            {

                processedChars.AddRange(processWord(word));

                word = new List<char>();

                processedChars.Add(c);

            }

            if(c.Equals(input.Last()))

            {

                processedChars.AddRange(processWord(word));

            }

        }

        return new string(processedChars.ToArray());

    }

​

    static bool isLetter(char c)

    {

        return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');

    }

​

    static List<char> processWord(List<char> chars)

    {   

        if(chars.Count() == 2)

        {

            // If the word is 2 letters then I put the first then zero and the last.

            return new List<char>{chars.ElementAt(0), '0', chars.ElementAt(1)};

        }

        if(chars.Count() == 1)

        {

            // If the word is a single letter then I put the singe letter on both sides of a zero since one letter is both first and last letter. Since there are no letters inbetween there can be no unique letters to count.

            return new List<char>{chars.ElementAt(0), '0', chars.ElementAt(0)}; 

        }

        var middlePortion = new List<char>();

        var newWord = new List<char>();

        newWord.Add(chars.ElementAt(0));

        for(int i = 1; chars.Count()-1 > i; i++)

        {   

            middlePortion.Add(chars.ElementAt(i));

        }

        var uniqueChars = new List<char>();

        uniqueChars.Add(middlePortion.ElementAt(0));

        foreach(char middleChar in middlePortion){

            for(var i = 0; uniqueChars.Count() > i; i++){

                if(middleChar == uniqueChars.ElementAt(i)){

                     break;

                }

                if(i == uniqueChars.Count()-1){

                    uniqueChars.Add(middleChar);

                }

            }

        }

        newWord.AddRange(uniqueChars.Count().ToString().ToCharArray());

        newWord.Add(chars.ElementAt(chars.Count()-1));

        return newWord;

    }

​

    public static void Main()

    {

        Console.WriteLine(shortenString("Fun to eat!"));

    }

}