2) Next step, push up 3 poxes as follow.
3) It is not hard to make this pattern.
4) It is an obvious step to clean them all then.
5) Next step, push 3 boxes at follow.
6) Push them down 1 step.
7) Push 2 boxes at the end of two center corridor towards right.
8) Push 1 step up as follow and you can find the way.
9) You can clean them one by one until this:
10) There is only one way: push up the center one. Finish.
