There are 4 shapes on a 6x6 grid. Which shape is closest to the brown rectangle in terms of Manhattan distance? The final answer is the grid position of the closest shape like (row_index, column_index).
<think>Target shape: brown rectangle at (5, 3)
Distance from target shape to green rectangle at (3, 4): 3
Distance from target shape to blue right_triangle at (2, 5): 5
Distance from target shape to purple right_triangle at (2, 4): 4
Closest shape is the green rectangle at (3, 4) with distance 3</think>

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