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

namespace BigTextReader
{
    class Program
    {
        static void Main(string[] args)
        {
            string path = "";
            do
            {
                Console.WriteLine("Please input the file path:");
                path = Console.ReadLine();
            }
            while (!System.IO.File.Exists(path));
            var fileStream = System.IO.File.OpenRead(path);
            while(true)
            {
                Console.WriteLine("Please input the start position:");
                var position = Int64.Parse(Console.ReadLine());
                if (position == -1)
                {
                    Console.WriteLine("finish");
                    return;
                }
                fileStream.Position = position;
                var byts = new Byte[1000];
                fileStream.Read(byts, 0, 1000);
                var str = Encoding.UTF8.GetString(byts);
                Console.WriteLine(str);
            }

        }
    }
}