Modify the program in Problem $5$ so that it also displays how much package A customers would save if they purchased package B or C$,$ and how much money Package B customers would save if they purchases Package C$.$ If there would be no savings, no message should be printed.

Note:

It is easier to first calculate the cost of all plans $($A$,$ B$,$ and C$)$ based on the number of minutes the user$-$entered. Then based on the plan user chose, compare, and calc. the difference among the plans.