There are 5 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 (5, 3)
Distance from target shape to orange trapezoid at (0, 3): 5
Distance from target shape to cyan right_triangle at (3, 5): 4
Distance from target shape to gray rectangle at (0, 0): 8
Distance from target shape to green square at (6, 4): 2
Closest shape is the green square at (6, 4) with distance 2</think>

<answer>(6, 4)</answer>