There are 3 shapes on a 8x8 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 (6, 3)
Distance from target shape to pink right_triangle at (2, 2): 5
Distance from target shape to green square at (5, 4): 2
Closest shape is the green square at (5, 4) with distance 2</think>

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