using System;

using System.Text;                  

public class Program

{

    public static void Main()

    {

        var str="AAZBBBY";

        var wordToChar=str.ToCharArray();

        var newChar=wordToChar[0];

        var sb=new StringBuilder();

        for(var i=1;i<wordToChar.Length;i++){

            if(newChar!=wordToChar[i]){

                sb.Append(newChar);

                newChar=wordToChar[i];

            }

        }

        Console.WriteLine(sb.ToString());

    }

}