Hell Zapper

Spoiler: Solution tip & trick

Tip
-B has to walk on long legs.
-If B moves to a lower place, B's legs get short and closer to Zapper.
-Stop in front of the new Zapper and move on.

Trick
-Move the slider so that B would fall from the original position.
-Cancel Tap
-Low Ceiling
-Quick tap like SSS(?)
-Zapper Walker

Spoiler: Video

At the level I made before, B passed Zapper safely without a trick.

In this version I can get through the top floor, but on the second floor the second zapper after the red brick cannot get through! I tried it many times - I'm sorry I didn't succeed.

@Denis Nazin It hasn't changed much from the previous version. You didn't consider the distance and height of B and zapper. You should look at the terrain carefully. The location of zapper on the low ceiling and the order of stairs are different. The zapper after the red brick is unaffected by the low ceiling. The video shows the scene of controlling B.