static void Main(string[] args)
        {
            Console.WriteLine("Welcome To Address Book Program");
            int    choice;
            string name;

            do
            {
                Console.WriteLine("\nMenu : \n 1.Add New Address Book \n 2.Work On Existing Address Book \n 3.View Contact By City or State \n4.Count by city \n 5.Save and Exit \n6.Exit");
                choice = Convert.ToInt32(Console.ReadLine());
                switch (choice)
                {
                case 1:
                    Console.WriteLine("Enter the Name of Address Book");
                    name = Console.ReadLine();
                    AddressBookMap.Add(name, new AddressBook());
                    break;

                case 2:
                    Console.WriteLine("Enter the Name of Address Book you wish to Work On");
                    name = Console.ReadLine();
                    AddressBook addressBook = AddressBookMap[name];
                    addressBook.FillAddressBook();
                    break;

                case 3:
                    foreach (Contact contact in ViewPersonByCityOrState())
                    {
                        System.Console.WriteLine(contact);
                        System.Console.WriteLine();
                    }
                    break;

                case 4:
                    CountPersonByCityOrState();
                    break;

                case 5:
                    foreach (KeyValuePair <string, AddressBook> kvp in AddressBookMap)
                    {
                        FileIO.WriteToFile(kvp.Value, kvp.Key);
                    }
                    break;
                }
            } while (choice != 6);
            // AddressBook book = FileIO.ReadFromFile("book");
            // foreach(Contact contact in book.ContactList)
            // {
            //     System.Console.WriteLine(contact);
            // }
        }