You are given three grids, where each of them is 5 by 5 in size.
Grids have empty cells marked with "▢" and filled cells marked with "X".
Your task is to generate a referring expression that best describes the target grid while distinguishing it from the two other distractor grids.
The first grid is the target grid, and the following two grids are the distractors.

Target grid:

X X X X ▢
X X X ▢ X
X X ▢ X X
X ▢ X X X
▢ X X X X

Distractor grid 1:

▢ X X X ▢
X ▢ X ▢ X
X X ▢ X X
X ▢ X ▢ X
▢ X X X ▢

Distractor grid 2:

▢ X X X X
X ▢ X X X
X X ▢ X X
X X X ▢ X
X X X X ▢

Instruction: Describe the target grid.
Generate the referring expression starting with the tag "Expression: " for the given target grid. Omit any other text.
Expression: The grid with a diagonal of empty cells from top-right to bottom-left, and all other cells filled with X's.
assistant
Expression: The target grid features a central "▢" surrounded by four "X" cells, with the "X" cells increasing in number as they move away from the central "▢". The first row and last row have two "X" cells, the second row has three "X" cells, the third row has four "X" cells, and the fourth row has three "X" cells.
assistant