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 contains three filled cells in the first row, with the first and third cells filled, and the second cell empty. The second row has two filled cells at the end, while the first three cells are empty. The third row has one filled cell at the end, with the first three cells empty. The fourth row has filled cells in the first and third positions, and the last row has two filled cells in the second and third positions, with the rest empty.
assistant
Expression: The target grid is the only one with a diagonal line of filled cells from the top left to the bottom right, and it has two filled cells in the top and second row's rightmost positions.
assistant