static void Main(string[] args) { var client = new LibraryClient(); client.IntroduceYourself(5, "Вася"); List <int> arr = new List <int> { 1, 2, 3 }; client.ChooseNewBooks(arr); client.HandOverBooks(new List <int> { 2, 3 }); client.ChooseNewBooks(arr); client.ApplayChanges(); client.GoAway(); Console.ReadKey(); }