There are 3 shapes on a 6x6 grid. Which shape is closest to the red 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: red right_triangle at (4, 5)
Distance from target shape to yellow square at (4, 1): 4
Distance from target shape to brown rectangle at (0, 5): 4
Closest shape is the yellow square at (4, 1) with distance 4</think>

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