There are 6 shapes on a 8x8 grid. Which shape is closest to the red 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: red square at (4, 0)
Distance from target shape to gray trapezoid at (6, 5): 7
Distance from target shape to green square at (0, 5): 9
Distance from target shape to purple square at (7, 3): 6
Distance from target shape to blue right_triangle at (2, 6): 8
Distance from target shape to cyan trapezoid at (3, 7): 8
Closest shape is the purple square at (7, 3) with distance 6</think>

<answer>(7, 3)</answer>