Longest Block in String

using System;

namespace Longest_block_In_string
{
    class Program
    {
        static void Main(string[] args)
        {
            string text = Console.ReadLine();
            int endIndex = 0;
            int index = 0;
            int count = 1;
            int maxCount = 0;
            int currIndex = 0;

            while (index != text.Length - 1)
            {
                if (text[index] == text[index + 1])
                {
                    currIndex = index + 1;
                    count++;

                }
                else
                {
                    count = 1;
                }

                if (count > maxCount)
                {
                    maxCount = count;
                    endIndex = currIndex;
                }
                index++;

            }

            int startIndex = endIndex - maxCount + 1;
            Console.WriteLine(text.Substring(startIndex, maxCount));
        }
    }
}