From a start door, go to the right.
There is a cracked ladder on the right-side edge and climb it.
When you got to the top of the ladder, there is a wooden box on your left.
Bring it upon an appearing ladder and go up to the upper brick.
Repeat the same action four times and get to the left edge.
Climb a ladder and go toward the right.
Appearing wooden boxes will fall down.
Pile up two fallen boxes on the right of a door to get to upper right floor.
Go up to the upper floor and climb a ladder on the right.
After you climbed it, there are six wooden boxes on your left.
Swallow three of them and pile them up on the ladder you've climbed.
After that, climb a ladder and go up to the further upper floor.
Swallow a wooden box and move to the right-side brick floor.
Release a box on the right edge to get a key.
After got a key, bring two wooden boxes from your left and drop them into the right edge.
Then go down and get on the two piled boxes you've dropped.
A goal door is placed next to six wooden boxes on your left so break them.