# The revenge of 3D light bulbs

This is a three-dimensional Akari puzzle (also known as Light Up). The five squares represent the layers of a $$5\times5\times5$$ cube, top to bottom. The objective is to add light bulbs into any number of cells so that the resulting grid satifies the following rules:1

• Black cells are walls and cannot contain light bulbs.
• Numbers in black cells indicate how many light bulbs are directly adjacent to that cell (vertically, horizontally or along the Z-axis).
• A light bulb illuminates its own cell as well as every cell visible from it in all six directions (up/down, right/left, and both ways along the Z-axis), continuing until a wall comes in the way.
• Every white square must be illuminated by at least one light bulb.
• No light bulb may be illuminated by another light bulb.

Note: The solution is unique and solvable by logic alone. No guesswork or trial-and-error is necessary here.

1 Paraphrased from the original rules on Nikoli