There are 3 shapes on a 8x8 grid. Which shape is closest to the purple right_triangle 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 right_triangle at (1, 5)
Distance from target shape to pink right_triangle at (2, 4): 2
Distance from target shape to brown right_triangle at (5, 5): 4
Closest shape is the pink right_triangle at (2, 4) with distance 2</think>

<answer>(2, 4)</answer>