using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace MatrixExercise
{
    class Program
    {
        static void Main(string[] args)
        {
            var sw = Stopwatch.StartNew();
            var union = new HashSet<Int32>();
            var result = new HashSet<Int32>();
            foreach (var row in GetRowFromFile("Matrix.txt"))
            {
                var copy = new int[row.Count];
                row.CopyTo(copy);
                row.IntersectWith(union);
                union.UnionWith(copy);
                result.UnionWith(row);
            }

            sw.Stop();
            Console.WriteLine("Time: " + sw.Elapsed);

            foreach (var i in result)
            {
                Console.WriteLine(i);
            }
            Console.ReadKey();
        }


        static IEnumerable<HashSet<int>> GetRowFromFile(string path)
        {
            return ReadLines(() => File.OpenText(path), ParseLine);
        }

        private static HashSet<Int32> ParseLine(string line)
        {
            var numbers = line.Split(' ');
            var intList = new HashSet<int>(numbers.Select(Int32.Parse));
            return intList;
        }

        static IEnumerable<T> ReadLines<T>(Func<TextReader> provider, Func<string, T> morpher)
        {
            using (var reader = provider())
            {
                string line;
                while ((line = reader.ReadLine()) != null)
                {
                    yield return morpher(line);
                }
            }
        }
    }
}