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 (1, 4)
Distance from target shape to purple right_triangle at (1, 1): 3
Distance from target shape to orange rectangle at (4, 1): 6
Distance from target shape to green rectangle at (7, 5): 7
Closest shape is the purple right_triangle at (1, 1) with distance 3</think>

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