There are 5 shapes on a 6x6 grid. Which shape is closest to the red square 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 square at (3, 3)
Distance from target shape to gray right_triangle at (5, 0): 5
Distance from target shape to green right_triangle at (3, 5): 2
Distance from target shape to blue right_triangle at (3, 1): 2
Distance from target shape to cyan trapezoid at (4, 5): 3
Closest shape is the green right_triangle at (3, 5) with distance 2</think>

<answer>(3, 5)</answer>