There are 4 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, 0)
Distance from target shape to blue square at (1, 1): 4
Distance from target shape to pink square at (0, 0): 4
Distance from target shape to green right_triangle at (3, 6): 7
Closest shape is the blue square at (1, 1) with distance 4</think>

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