Remove sequence

using System;

namespace test
{
    internal class Program
    {
        private static void Main(string[] args)
        {
            Console.WriteLine("Enter the length of the marble sequence");
            int length = int.Parse(Console.ReadLine());

            string[] marbles = new string[length];
            for (int i = 0; i < length; i++)
            {
                marbles[i] = Console.ReadLine();
            }

            bool sequence = true;
            while (sequence)
            {
                sequence = false;
                for (int i = 0; i < marbles.Length; i++)
                {
                    for (int j = 0; j < marbles[i].Length - 2; j++)
                    {
                        if (marbles[i][j] != marbles[i][j + 1] || marbles[i][j] != marbles[i][j + 2])
                        {
                            continue;
                        }

                        marbles[i] = marbles[i].Substring(0, j) + marbles[i].Substring(j + 3, marbles[i].Length - j - 3);
                        sequence = true;
                        break;
                    }
                }
            }

            for (int i = 0; i < marbles.Length; i++)
            {
                Console.WriteLine(marbles[i]);
            }
        }
    }
}