There are 4 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 (4, 7)
Distance from target shape to yellow right_triangle at (5, 6): 2
Distance from target shape to pink square at (3, 5): 3
Distance from target shape to green rectangle at (2, 7): 2
Closest shape is the yellow right_triangle at (5, 6) with distance 2</think>

<answer>(5, 6)</answer>