There are 4 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 (5, 0)
Distance from target shape to purple right_triangle at (1, 0): 4
Distance from target shape to green square at (6, 7): 8
Distance from target shape to gray rectangle at (6, 1): 2
Closest shape is the gray rectangle at (6, 1) with distance 2</think>

<answer>(6, 1)</answer>