driver at a java bean warehouse. It's your job to put all of the crates of
java beans 
in their
places 
. Because
you've got a bulldozer (and not a forklift, which might have been more
appropriate), you can only push the crates. The crates are also quite
heavy, so you can only push one at a time.
Be careful! If you push boxes into the corners, or pack a group of boxes together, you'll get stuck. Just in case you do get stuck, you can undo your mistakes.