static void Main(string[] args)
        { /* UC6:- Refactor to add multiple Address Book to the System.
           *     Each Address Book has a unique Name
           *     - Use Console to add new Address Book
           *     - Maintain Dictionary of Address Book Name to Address Book
           */
            Console.WriteLine("**** Welcome To Address Book System ****");
            AddressBookDetails addressBookDetails = AddressBookDetails.ReadFromFile();
            bool flag = true;

            while (flag)
            {
                Console.Write("\n1.Add Address Book System" +
                              "\n2.Show Address Book System Name" +
                              "\n3.Delete Address Book" +
                              "\n4.Search Person in City or State " +
                              "\n5.Show all Record in City or State" +
                              "\n6.Count of Record City or State" +
                              "\n7.Exit\nEnter Your Choice: - ");

                int choice = Convert.ToInt32(Console.ReadLine());
                switch (choice)
                {
                case 1:
                    addressBookDetails.AddAddressBook();     // add new Address book
                    break;

                case 2:
                    addressBookDetails.ViewAllAddressBooks();     //view all address book names
                    break;

                case 3:
                    addressBookDetails.DeleteAddressBook();     //delete an address book
                    break;

                case 4:
                    try
                    {                                                      /* UC8:- Ability to search Person in a City or State across the multiple AddressBook
                                                                            *       - Search Result can show multiple person in the city or state
                                                                            */
                        Console.Write("1.City\n2.State\nEnter Choice:-");  //print
                        int choice2 = Convert.ToInt32(Console.ReadLine()); //take input and convert int32
                        if (choice2 == 1)                                  //check condition
                        {
                            addressBookDetails.SearchInCity();             //search city
                        }
                        else if (choice2 == 2)
                        {
                            addressBookDetails.SearchInState();//search State
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    break;

                case 5:
                    try
                    {                                                      /* UC8:- Ability to search Person in a City or State across the multiple AddressBook
                                                                            *        - Search Result can show multiple person in the city or state
                                                                            */
                        Console.Write("1.City\n2.State\nEnter Choice:-");  //print
                        int choice3 = Convert.ToInt32(Console.ReadLine()); //take input and convert int32
                        if (choice3 == 1)
                        {
                            addressBookDetails.ViewAllByCity();  //  view all contact in a city
                        }
                        else if (choice3 == 2)
                        {
                            addressBookDetails.ViewAllByState();  // view all contact in a State
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    break;

                case 6:
                    try
                    {                                                      /* UC10:- Ability to get number of contact persons i.e. count by City or State.
                                                                            *       - Search Result will show count by city and by state.
                                                                            */
                        Console.Write("1.City\n2.State\nEnter Choice:-");  //print
                        int choice4 = Convert.ToInt32(Console.ReadLine()); //take input and convert int32
                        if (choice4 == 1)
                        {
                            addressBookDetails.CountAllByCity(); //get count of contacts in City
                        }
                        else if (choice4 == 2)
                        {
                            addressBookDetails.CountAllByState(); //get count of contacts in state
                        }
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(ex.Message);
                    }
                    break;

                case 7:

                    flag = false;
                    break;

                default:
                    Console.WriteLine("Please Enter Valid Option");
                    break;
                }
            }

            // UC 13 Writing to the previously stored records.
            addressBookDetails.WriteToFile();
        }