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

<answer>(4, 6)</answer>