There are 4 shapes on a 6x6 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 (5, 0)
Distance from target shape to red square at (1, 2): 6
Distance from target shape to brown rectangle at (5, 4): 4
Distance from target shape to pink trapezoid at (2, 1): 4
Closest shape is the brown rectangle at (5, 4) with distance 4</think>

<answer>(5, 4)</answer>