using System;
using System.Collections.Generic;
using System.Linq;

namespace DNA
{
    class Program
    {
        static void Main()
        {
            var dna = "TTTAAAAAGGTTTAAAAAGGAAAACCCCCCAAAAACCCCCAAAAACCCCCCAAAAAGGGTTTAAAAGAAAACCCCCAGGGTTTAGGGTTTAAAAAAGGGTTTA";
            var duplicateSequences = Analyze(dna);
            foreach (var item in duplicateSequences)
            {
                Console.WriteLine(item);
            }
        }

        public static IEnumerable<string> Analyze(string dna)
        {
            var workCollection = new HashSet<string>();
            var outputCollection = new HashSet<string>();

            for (int i = 0; i < dna.Length; i++)
            {
                if (dna.Length - i < 10)
                {
                    break;
                }
                var temp = string.Empty;
                for (int j = i; j < i + 10; j++)
                {
                    temp += dna[j];
                }
                if(workCollection.Add(temp))
                {
                    continue;
                }
                else
                {
                    outputCollection.Add(temp);
                }

            }
            return outputCollection;
        }

    }
}