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

Distractor grid 1:

X X ▢ X X
X 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 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 features a central row completely empty, surrounded by filled cells, with the pattern of filled cells forming a border on the top, bottom, and sides, while the two adjacent grids either have no empty central row or have filled cells in the central row.
assistant
Expression: Contains a distinct pattern of "▢" and "X" in a specific arrangement. 
<end_of_turn>
assistant