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

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 grid with all X's forming a right-angled triangle along the left side.
assistant
Expression: The target grid has an X in the center cell of the 5x5 grid, with all cells in the top row and all cells in the leftmost column filled with X.

This description distinguishes the target grid from distractor grid 1, which does not have an X in the center cell, and distractor grid 2, which has some cells filled with X in the rightmost column and bottom row.
assistant