There are 3 shapes on a 8x8 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 (1, 3)
Distance from target shape to green rectangle at (5, 3): 4
Distance from target shape to red square at (2, 5): 3
Closest shape is the red square at (2, 5) with distance 3</think>

<answer>(2, 5)</answer>