There are 4 shapes on a 9x9 grid. Which shape is closest to the purple square in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: purple square at (7, 8)
Distance from target shape to red right_triangle at (8, 5): 4
Distance from target shape to gray square at (5, 2): 8
Distance from target shape to brown right_triangle at (1, 6): 8
Closest shape is the red right_triangle at (8, 5) with distance 4</think>

<answer>(8, 5)</answer>