Overtime on the factory floor

A garment factory in Dhaka pays its machine operators weekly. The first 40 hours are paid at the normal hourly rate. Hours above 40 up to 50 are paid at 1.5 times the rate, and hours above 50 are paid at double the rate.

Task: read two lines: the hourly rate (a number with up to 2 decimals) and the hours worked in the week (a multiple of 0.25, at most 80). Print Gross: X where X is the gross pay rounded to 2 decimals with halves rounded up, always showing 2 decimals.