23.zadacha

using System;
using System.Text;
class Program
{
    static void Main()
    {
        StringBuilder st = new StringBuilder("aaaaabbbbbcdddeeeedssaa");
        for (int i = 0,index=0; i < st.Length-1; i++,index++)
        {
            char currentLatter = st[i];
            while (index<st.Length-1 &&currentLatter == st[index+1])
            {
                st.Remove(index+1, 1);
            }
        }
        Console.WriteLine(st);
    }
}