public static void Main(string[] args)
        {
            //Student Database
            person[] database = new person[150];


            //Student's position in the database
            int studentStatus = 0;

            //Condition for the program to stay running
            bool maineMenu_isalive = true;


            //Main menu
            while (maineMenu_isalive)
            {
                try
                {
                    int select = Convert.ToInt32(menu());
                    switch (select)
                    {
                    case 1:                             //Add student
                    {
                        Console.Clear();
                        person adds = addStudent();
                        database[studentStatus] = adds;
                        studentStatus++;
                        Console.ReadKey();
                        break;
                    }

                    case 2:                             //Show student
                        int numberStudent = 0;          //The number opposite the name in the list
                        {
                            if (database[0] == null)
                            {
                                Console.WriteLine("\nNo information was entered from the students");
                                Console.ReadKey();
                            }
                            else
                            {
                                Console.Clear();
                                foreach (person student in database)
                                {
                                    numberStudent = numberStudent + 1;
                                    Console.WriteLine(numberStudent + ") full name : " + student.name + " " + student.family);
                                }

                                Console.ReadKey();
                            }
                            break;
                        }

                    case 3:                             //exit
                    {
                        Console.Clear();
                        maineMenu_isalive = false;
                        break;
                    }

                    default:                             //Wrong option
                    {
                        Console.Clear();
                        Console.WriteLine("The entered option is incorrect");
                        Console.ReadKey();
                        break;
                    }
                    }
                }
                catch (NullReferenceException)
                {
                    Console.WriteLine("\npleas enter number of student : ");
                    int  studentSelection     = showStdOption();
                    bool showStdOption_isaliv = true;
                    while (showStdOption_isaliv)
                    {
                        try
                        {
                            person selectedSudent = database[studentSelection];
                            Console.Clear();
                            Console.WriteLine("name: " + selectedSudent.name + "\nfamily: " + selectedSudent.family + "\nage: " + selectedSudent.age + "\naverage: " + selectedSudent.average);
                            showStdOption_isaliv = false;
                            Console.ReadKey();
                        }
                        catch
                        {
                            Console.WriteLine("\nEnter only the number in front of the student's name");
                            Console.ReadKey();
                            showStdOption_isaliv = false;
                        }
                    }
                }
                catch
                {
                    Console.WriteLine("The entered option is incorrect");
                    Console.ReadKey();
                }
            }
        }