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

Distractor grid 1:

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

Distractor grid 2:

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 target grid has a border of filled cells (X) on all four sides, with the top and bottom rows completely filled with Xs. The second and fourth rows have a single X at the beginning, followed by four empty cells (▢). The third row has three Xs at the beginning, followed by two empty cells (▢).
assistant
Expression: The target grid features a central row of four empty cells, with two filled rows above and below, and a symmetrical arrangement of filled and empty cells on either side.
assistant