static void Main()
        {
            bool operation = true; int n;

            while (operation == true)
            {
                Console.WriteLine("\n=== Github Job crawler program ===");
                Console.WriteLine("Please choose your operation:");
                Console.WriteLine("[1] Grab all jobs information that having specific description");
                Console.WriteLine("[2] Grab Part-time jobs information that having specific description");
                Console.WriteLine("[0] Exit");
                Console.WriteLine("\n Your Operation is:");
                try
                {
                    n = Convert.ToInt32(Console.ReadLine());
                }
                catch (Exception)
                {
                    Console.WriteLine("Invalid operation!");
                    n = 3;
                }
                switch (n)
                {
                case 0:
                    operation = false;
                    Console.WriteLine("Thank you!");
                    break;

                case 1:
                    Console.WriteLine("Please input the job description:");
                    string x = Console.ReadLine();
                    Crawler.CrawlAll(x);
                    break;

                case 2:
                    Console.WriteLine("Please input the job description:");
                    string y = Console.ReadLine();
                    Crawler.CrawlParttime(y);
                    break;

                case 3:
                    break;
                }
            }
            Console.WriteLine("\n Made by Huynh Thai Hieu");
            Console.ReadKey();
        }