Write a program that inputs salary and net sale then calculates the commission from the
net sale by using the below condition and displays the result on the screen. Repeat this
process until reach the sub-question 1.1-1.3
1.1. Using while and end program when the salary is equal to zero
1.2. Using do-while and end program when the salary is equal to zero
1.3. Using for and repeat it four times