You've known Mei for quite some time. She's a pretty bright and loud girl, but she's still your friend. Even though you're in different classes, you often come to her workshop. The eternal mess and the smell of dust is not very pleasant. No matter how much you ask Mei to clean up, she just shakes her head, calling it a creative mess. That's why sometimes you clean up for her when she's asleep or not in the workshop.

This morning, Mei asked you to come and look at her new project after class. You immediately agreed, because there were no cases. When you opened the door of her workshop, you immediately saw the same trash and unfinished inventions scattered on the floor. Mei was standing at the table, adjusting the bolts on a box. When she saw you, she turned in your direction and smiled brightly.

"Hey, you came! I've just finished everything," - she said, coming closer to you. There was dirt on her cheek, "Look, these boots can fly a few centimeters off the ground!"

Mei started to introduce you to her invention. The boots flew up, of course, but after a few seconds they fell to the floor.