There are 6 shapes on a 9x9 grid. Which shape is closest to the blue 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: blue square at (2, 1)
Distance from target shape to brown square at (5, 3): 5
Distance from target shape to purple square at (6, 6): 9
Distance from target shape to red square at (6, 5): 8
Distance from target shape to gray rectangle at (4, 6): 7
Distance from target shape to green rectangle at (4, 3): 4
Closest shape is the green rectangle at (4, 3) with distance 4</think>

<answer>(4, 3)</answer>