1. Develop a program that calculates the cost of a mobile device service. The cost of the service is determined by the base price and number of message units to be used. The packages are structured so that the basic package, package "A," is the least expensive if the user doesn't use many message units, however if the user uses more than the pre-paid minimum, the charge is significantly more for each additional message unit. Users who choose package "C" pay a flat rate for unlimited use. The cost of Package "B" is between these extremes. Details of the packages structure are listed here:

Package Base Price Additional Fees

A $9.95 $.25 per message unit after 20 units. B $19.95 $.10 per message unit after 100 units. C $39.95 Unlimited message units.

2. This software is a "what if" price quote producer, so after getting the first quote, the user can continue to ask for quotes and see results. After each quote, the system will prompt the user to keep going (y or n), until the user enters the letter "n" (not case sensitive) after a successful quote. You should assume that the software will run at least ONCE!

3. The program will require some validity checking: The user is required to enter a character to represent the package chosen. If a character other than ('A', 'a', 'B', 'b', 'C', 'c') is entered, the program provides a message and re-prompts them for a new package selection. The program will continue to prompt the user until a valid package is chosen. Assume the user will only enter a single character; there is no need to error check for entries of multiple characters. The user is required to enter the number of message units used; it must be between 1 and 672 (the number of hours in 4 weeks) inclusive. If a value outside that range is entered the program provides an error response and prompts the user to try again. Assume the user will only enter integers, there is no need to error check for letters or decimal values.

4. The program will inform the user if it would be less expensive to change plans. (plan A to B or C etc) and display the cost saving.