## Editorial for Mock CCC '19 Contest 2 S1 - Tudor's Double Doors

Remember to use this editorial only when stuck, and not to copy-paste code from it. Please be respectful to the problem author and editorialist.

Submitting an official solution before solving the problem yourself is a bannable offence.

The area of half a rectangle with side lengths and is .

To print it accurate to one decimal place, the exact area should be stored in a 64-bit integer and then either .0 or .5 needs to be printed depending on the parity of .