There are 5 shapes on a 8x8 grid. Which shape is closest to the blue 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: blue right_triangle at (3, 7)
Distance from target shape to pink right_triangle at (2, 4): 4
Distance from target shape to red rectangle at (3, 6): 1
Distance from target shape to brown rectangle at (5, 6): 3
Distance from target shape to gray trapezoid at (4, 4): 4
Closest shape is the red rectangle at (3, 6) with distance 1</think>

<answer>(3, 6)</answer>