static void Main(string[] args) { string InputSymbol; var ListOfCountries = new Dictionary <int, Country>() { { 1, new Country { Name = "Armenia", ID = 1 } }, { 2, new Country { Name = "England", ID = 2 } }, { 3, new Country { Name = "Germany", ID = 3 } } }; Country.Count = 3; var ListOfCities = new Dictionary <int, City>(); var ListOfUniversities = new Dictionary <int, University>(); var ListOfFaculties = new Dictionary <int, Faculty>(); var ListOfLecturers = new Dictionary <int, Lecturer>(); var ListOfStudents = new Dictionary <int, Student>(); Console.WriteLine("1a: . . Add new Country\n" + "1b: . . Get Country\n" + "1c: . . Delete Country\n" + "1d: . . Update Country\n"); Console.WriteLine("2a: . . Add new City\n" + "2b: . . Get City\n" + "2c: . . Delete City\n" + "2d: . . Update City\n"); Console.WriteLine("3a: . . Add new University\n" + "3b: . . Get University\n" + "3c: . . Delete University\n" + "3d: . . Update University\n"); Console.WriteLine("4a: . . Add new Faculty\n" + "4b: . . Get Faculty\n" + "4c: . . Delete Faculty\n" + "4d: . . Update Faculty\n"); Console.WriteLine("5a: . . Add new Lecturer\n" + "5b: . . Get Lecturer\n" + "5c: . . Delete Lecturer\n" + "5d: . . Update Lecturer\n"); Console.WriteLine("6a: . . Add new Student\n" + "6b: . . Get Student\n" + "6c: . . Delete Student\n" + "6d: . . Update Student\n"); Console.WriteLine("{0}Help{1}\n", new string('-', 10), new string('-', 10)); Console.WriteLine("1h: . . Show Countries\n" + "2h: . . Show Cities\n" + "3h: . . Show Universities\n" + "4h: . . Show Faculties\n" + "5h1: . . Show Lecturers of This Universities\n" + "5h2:. . Show Lecturers of This Faculties\n" + "6h1:. . Show Students of This Universities\n" + "6h2:. . Show Students of This Faculties\n" + "Press q to exit:․․\n"); do { InputSymbol = Console.ReadLine(); switch (InputSymbol) { case "3a": UniversityServices.AddUniversity(ref ListOfUniversities, ref ListOfCountries, ref ListOfCities); break; case "3b": UniversityServices.GetUniversity(ref ListOfUniversities); break; case "3c": UniversityServices.RemoveUniversity(ref ListOfUniversities); break; case "3d": UniversityServices.UpdateUniversity(ref ListOfUniversities); break; case "2a": Console.WriteLine(CityServices.AddCity(ref ListOfCountries, ref ListOfCities)); break; case "2b": Console.WriteLine(CityServices.GetCity(ref ListOfCities)); break; case "2c": Console.WriteLine(CityServices.RemoveCity(ref ListOfCities)); break; case "2d": Console.WriteLine(CityServices.UpdateCity(ref ListOfCities)); break; case "1a": Console.WriteLine(CountryServices.AddCountry(ref ListOfCountries)); break; case "1b": Console.WriteLine(CountryServices.GetCountry(ref ListOfCountries)); break; case "1c": Console.WriteLine(CountryServices.RemoveCountry(ref ListOfCountries)); break; case "4a": Console.WriteLine(FacultyServices.AddFaculty(ref ListOfUniversities, ref ListOfFaculties)); break; case "4b": Console.WriteLine(FacultyServices.GetFaculty(ref ListOfFaculties)); break; case "4c": FacultyServices.RemoveFaculty(ref ListOfFaculties); break; case "4d": FacultyServices.UpdateFaculty(ref ListOfFaculties); break; case "5a": LecturerServices.AddLecturer(ref ListOfUniversities, ref ListOfLecturers); break; case "5b": LecturerServices.GetLecturer(ref ListOfLecturers); break; case "5c": LecturerServices.RemoveLecturer(ref ListOfLecturers); break; case "5d": LecturerServices.UpdateLecturer(ref ListOfLecturers); break; case "1d": Console.WriteLine(CountryServices.UpdateCountry(ref ListOfCountries)); break; case "6a": StudentsServices.AddStudent(ref ListOfUniversities, ref ListOfStudents); break; case "6b": StudentsServices.GetStudent(ref ListOfStudents); break; case "6c": StudentsServices.RemoveStudent(ref ListOfStudents); break; case "6d": StudentsServices.UpdateStudent(ref ListOfStudents); break; case "1h": CountryServices.ShowCountries(ref ListOfCountries); break; case "2h": CityServices.ShowCities(ref ListOfCities); break; case "3h": UniversityServices.ShowUniversities(ref ListOfUniversities); break; case "4h": FacultyServices.ShowFaculties(ref ListOfFaculties); break; case "5h1": LecturerServices.LecturersOfThisUniversity(ref ListOfUniversities); break; case "5h2": LecturerServices.LecturersOfThisFaculty(ref ListOfFaculties); break; case "6h1": StudentsServices.StudentsOfThisUniversity(ref ListOfUniversities); break; case "6h2": StudentsServices.StudentsOfThisFaculty(ref ListOfFaculties); break; default: if (InputSymbol == "q") { break; } else { Console.WriteLine("Please enter correct symbol"); break; } } }while (InputSymbol != "q"); }