There are 6 shapes on a 7x7 grid. Which shape is closest to the purple 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: purple rectangle at (5, 0)
Distance from target shape to gray right_triangle at (2, 1): 4
Distance from target shape to brown right_triangle at (6, 2): 3
Distance from target shape to green rectangle at (3, 6): 8
Distance from target shape to red rectangle at (4, 0): 1
Distance from target shape to blue trapezoid at (6, 4): 5
Closest shape is the red rectangle at (4, 0) with distance 1</think>

<answer>(4, 0)</answer>