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

Distractor grid 1:

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

Distractor grid 2:

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 solid row of four filled cells at the top, followed by a completely empty second row. In the third row, there are filled cells at the first, third, and fifth positions, with empty cells in the second and fourth positions. The fourth row has a filled cell at the far right, with the rest empty, and the bottom row contains two filled cells at the fourth and fifth positions, with three empty cells preceding them.
assistant
Expression: Contains a distinct pattern of "X" and "▢" with a specific arrangement of "X"s in the top row and bottom row. 
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assistant