using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        Console.WriteLine(compressValue("AAaBCbb"));        

    }

    public static string compressValue(string word){

        word =  word.ToLower();

        var test = word.ToCharArray();

        var result = "";

        foreach(var letter in test.Distinct()){

            string count = test.Count(x=>x == letter) > 1 ?  "x" + test.Count(x=>x == letter).ToString() + "+" : "";    

            result += letter + count;   

        }

        return result;

    }

}