There are 3 shapes on a 8x8 grid. Which shape is closest to the green 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: green square at (6, 6)
Distance from target shape to red square at (1, 3): 8
Distance from target shape to blue right_triangle at (2, 5): 5
Closest shape is the blue right_triangle at (2, 5) with distance 5</think>

<answer>(2, 5)</answer>