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

<answer>(5, 3)</answer>