There are 3 shapes on a 8x8 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 (6, 6)
Distance from target shape to brown right_triangle at (6, 0): 6
Distance from target shape to yellow right_triangle at (6, 2): 4
Closest shape is the yellow right_triangle at (6, 2) with distance 4</think>

<answer>(6, 2)</answer>