There are 5 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 (2, 4)
Distance from target shape to blue right_triangle at (3, 4): 1
Distance from target shape to cyan rectangle at (2, 5): 1
Distance from target shape to pink square at (1, 5): 2
Distance from target shape to red right_triangle at (2, 1): 3
Closest shape is the blue right_triangle at (3, 4) with distance 1</think>

<answer>(3, 4)</answer>