There are 3 shapes on a 4x4 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 (1, 3)
Distance from target shape to gray right_triangle at (0, 2): 2
Distance from target shape to brown right_triangle at (0, 3): 1
Closest shape is the brown right_triangle at (0, 3) with distance 1</think>

<answer>(0, 3)</answer>