There are 4 shapes on a 8x8 grid. Which shape is closest to the gray 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: gray right_triangle at (2, 3)
Distance from target shape to yellow trapezoid at (0, 7): 6
Distance from target shape to brown trapezoid at (5, 1): 5
Distance from target shape to blue right_triangle at (7, 0): 8
Closest shape is the brown trapezoid at (5, 1) with distance 5</think>

<answer>(5, 1)</answer>