static void Main(string[] args) { Console.Write("Enter 0 for open exist file or other for create new: "); var isNew = Console.ReadLine() != "0"; string fileName = ReadFileName(args, isNew); var doc = AbstractHandler.CreateInstance(fileName); var type = doc switch { XMLHandler => "xml", DOCHandler => "doc", _ => "txt", }; doc.Open(); doc.Save(); Console.WriteLine($"Type of file'{fileName}' is {type}"); _ = Console.ReadKey(); }