Push-Over

You're playing a small ant that is willing to help a friend in rather inconvenient situation. Apparently, your friend, doggie, likes to eat cookies that has his picture on their box, and he got himself so carried away that he lost the balance, and a bag of cookies fell deep down into an ant-hill. Now, you're goin' in, in a mission of solving puzzles, and retrieving the cookies for your friend. Now, this ant-hill is a bit different from the ones you saw, and especially from the one you live in. It's path is filled up with boulders, and all the gates, and you must travel the quest to find the cookies. After each different place inside, you'll find a small bag of cookie, and bring it back to your friend doggie. The main quest consists of you carrying your-size boulders, and placing them in a well imagined line, so when you push the exact one, all must fall, and the one that marks the end must fall the last, or the door will stay shut permanently. Beside we know that ants are very easy, and can live almost every fall, you cannot practice that, so if you jump from a little bit too high position, don't expect much, but to retry the level.