The program will repeatedly read the product prices until the user enter (-1).
The program will ask the user to enter a discount code if any.
Assume that there is only one discount code which is "BePositive" and it will deduct 20% of the
total price of the products.
Total price = Total - (Total x 0.20)
In case the user enters a discount code:
The program will print the total price before and after the discount code (See Examplel).,
Otherwise:
The program will print the total price only