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 (1, 6)
Distance from target shape to blue rectangle at (5, 4): 6
Distance from target shape to pink square at (1, 0): 6
Closest shape is the blue rectangle at (5, 4) with distance 6</think>

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