There are 3 shapes on a 6x6 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 (3, 5)
Distance from target shape to pink right_triangle at (3, 1): 4
Distance from target shape to red right_triangle at (1, 4): 3
Closest shape is the red right_triangle at (1, 4) with distance 3</think>

<answer>(1, 4)</answer>