There are 4 shapes on a 8x8 grid. Which shape is closest to the gray 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: gray square at (4, 3)
Distance from target shape to pink trapezoid at (6, 1): 4
Distance from target shape to red square at (5, 3): 1
Distance from target shape to cyan square at (3, 5): 3
Closest shape is the red square at (5, 3) with distance 1</think>

<answer>(5, 3)</answer>