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 has a filled row at the top with four "X" cells followed by one empty cell, the second row has three "X" cells with an empty cell in the fourth position, the third row has two "X" cells followed by an empty cell and two "X" cells, the fourth row has one empty cell followed by three "X" cells, and the last row has one empty cell at the beginning followed by four "X" cells.
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Expression: The grid where the top row is completely filled except for the last cell, and the bottom row is completely filled except for the first cell.
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