There are 2 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 (1, 5): 2
Closest shape is the green rectangle at (1, 5) with distance 2</think>

<answer>(1, 5)</answer>