You are working as an apprentice to a landscape architect. Your first assignment is to plant some trees in a client's large, flat lawn. Your boss tells you:
"I want you to plant 16 trees in 15 rows. There must be exactly 4 trees in each row."
How should you plant the trees if you want to complete your assignment?
you must define a row: is it only horizontal and vertical, or can it be diagonal also?