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 target grid has a top row fully filled with "X" except for the last cell, and the bottom row has two consecutive "X" at the end. The third row has "X" in the first, third, and fifth cells, and the fourth row has a single "X" at the end.
assistant
Expression: The first grid has a pattern of Xs in the top row and a cluster of Xs in the bottom left corner. 

assistant