static void Main(string[] args)
        {
            var bookService = new BookListService(new FileBookRepository("default"));

            bookService.AddBook(new Book("J. Richter", "C# via", 500.0, 800));
            bookService.AddBook(new Book("D. Samal", "Sifo VMSIS", 350.0, 85));
            bookService.AddBook(new Book("A. Pushkin", "E.Onegin", 110.0, 150));
            bookService.AddBook(new Book("L. Tolstoi", "Voina i mir", 650.0, 1000));
            bookService.AddBook(new Book("S. Perro", "Kot v sapogah", 60.0, 50));

            foreach (var book in bookService.BookList)
            {
                Console.WriteLine($"{book}");
            }

            bookService.DeleteBook(new Book("L. Tolstoi", "Voina i mir", 650.0, 1000));
            bookService.DeleteBook(new Book("S. Perro", "Kot v sapogah", 60.0, 50));
            Console.WriteLine("------------------------------------------");

            foreach (var book in bookService.BookList)
            {
                Console.WriteLine($"{book}");
            }

            Console.WriteLine("------------------------------------------");
            bookService.Sort(new BookComparer());

            foreach (var book in bookService.BookList)
            {
                Console.WriteLine($"{book}");
            }

            Console.WriteLine("------------------------------------------");

            var selectedBooksByTag = bookService.FindBooksByTags(b => b.Author.Contains('S'.ToString()));

            foreach (var book in selectedBooksByTag)
            {
                Console.WriteLine($"{book}");
            }

            bookService.Repository.Save(bookService.BookList);
            Console.ReadKey();
        }