static void Main(string[] args)
        {
            Person person = new ConcretePerson("Sergey", "Sergeev", 2);
            person.IntroduceYourself(person);
            Console.WriteLine();

            person.Age = 30;
            person.IntroduceYourself(person);
            Console.WriteLine();

            Person studentPerson = new StudentConcretePerson("Petr", "Petrov", 24, 3);
            studentPerson.IntroduceYourself(studentPerson);
            Console.WriteLine();

            Person extramuralStudentPerson = new ExtramuralStudentConcretePerson("Ivan", "Ivanov", 20,2);
            extramuralStudentPerson.IntroduceYourself(extramuralStudentPerson);

            Console.ReadKey();
        }
        static void Main(string[] args)
        {
            Person person = new ConcretePerson("Sergey", "Sergeev", 2);

            person.IntroduceYourself(person);
            Console.WriteLine();

            person.Age = 30;
            person.IntroduceYourself(person);
            Console.WriteLine();

            Person studentPerson = new StudentConcretePerson("Petr", "Petrov", 24, 3);

            studentPerson.IntroduceYourself(studentPerson);
            Console.WriteLine();

            Person extramuralStudentPerson = new ExtramuralStudentConcretePerson("Ivan", "Ivanov", 20, 2);

            extramuralStudentPerson.IntroduceYourself(extramuralStudentPerson);

            Console.ReadKey();
        }