There are 6 shapes on a 8x8 grid. Which shape is closest to the yellow 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: yellow rectangle at (6, 3)
Distance from target shape to pink square at (5, 4): 2
Distance from target shape to orange square at (3, 7): 7
Distance from target shape to green square at (5, 7): 5
Distance from target shape to purple right_triangle at (6, 6): 3
Distance from target shape to gray square at (1, 3): 5
Closest shape is the pink square at (5, 4) with distance 2</think>

<answer>(5, 4)</answer>