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 (4, 3)
Distance from target shape to gray rectangle at (1, 5): 5
Distance from target shape to yellow right_triangle at (5, 0): 4
Closest shape is the yellow right_triangle at (5, 0) with distance 4</think>

<answer>(5, 0)</answer>