static void Main(string[] args)
        {
            int            ans;
            ConsoleKeyInfo cki;

            Console.WindowHeight = 50;
            Console.WindowWidth  = 100;
            do
            {
                Console.Clear();
                Console.WriteLine("Hello dear student, please enter your firstName");
                string firstName = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your lastName");
                string lastName = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your student number");
                string studentNumber = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your age");
                int age = Convert.ToInt32(Console.ReadLine());
                Console.Clear();
                Console.WriteLine("please enter your street number");
                string stnumber = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your street");
                string street = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your city");
                string city = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("please enter your country");
                string country = Console.ReadLine();
                Console.Clear();
                Console.WriteLine("How many scores do you want to save ?");
                int scoreNumber = Convert.ToInt32(Console.ReadLine());
                Console.Clear();
                int[] score = new int[scoreNumber];
                for (int i = 0; i < score.Length; i++)
                {
                    score[i] = Convert.ToInt32(Console.ReadLine());
                    Console.Clear();
                }

                Adress adress = new Adress(number, street, city, country);

                Student s = new Student(firstName, lastName, studentNumber, age, adress, score);



                do
                {
                    Console.WriteLine(" tape 1  for displaying your average score ");
                    Console.WriteLine(" tape 2  for displaying your adress ");
                    Console.WriteLine(" tape 3  for displaying your city ");
                    Console.WriteLine(" tape 4  for displaying all of your informations ");



                    int ex = Convert.ToInt32(Console.ReadLine());
                    switch (ex)
                    {
                    case 1:
                        Console.Clear();
                        Console.WriteLine(s.FirstName + " " + s.LastName + " average score is " + s.averageScore);
                        Console.WriteLine();
                        Console.WriteLine("press enter to continue");
                        Console.ReadKey();


                        break;


                    case 2:
                        Console.Clear();
                        Console.WriteLine(s.FirstName + " " + s.LastName + adress.ToString());
                        Console.WriteLine();
                        Console.WriteLine("press enter to continue");
                        Console.ReadKey();
                        break;

                    case 3:
                        Console.Clear();
                        Console.WriteLine(s.FirstName + " " + s.LastName + " is living in " + adress.City);
                        Console.WriteLine();
                        Console.WriteLine("press enter to continue");
                        Console.ReadKey();
                        break;

                    case 4:
                        Console.Clear();
                        s.ToString(adress, s);
                        Console.WriteLine();
                        Console.WriteLine("press enter to continue");
                        Console.ReadKey();
                        break;
                    }
                    Console.Clear();

                    Console.WriteLine("Tape the escape key to leave the program");
                    Console.WriteLine("Tape 5 to see check other informations on this student");
                    Console.WriteLine("are any other keys to continu with an other student");
                    ans = Convert.ToInt32(Console.ReadLine());

                    Console.Clear();
                } while (ans == 5);
                cki = Console.ReadKey();
            } while (cki.Key != ConsoleKey.Escape);

            Console.Read();
        }
        // constructor


        public Student(string firstName, string lastName, string studentNumber, int age, Adress adress, int[] score) :
            base(firstName, lastName)
        {
            this.firstName     = firstName;
            this.lastName      = lastName;
            this.studentNumber = studentNumber;
            this.age           = age;
            this.adress        = adress;
            this.score         = score;

            int sum = 0;

            for (int i = 0; i < score.Length; i++)
            {
                sum += score[i];
            }
            averageScore    = sum / score.Length;
            this.fullName   = firstName + " " + lastName;
            this.fullAdress = adress.ToString();
        }