There are 5 shapes on a 7x7 grid. Which shape is closest to the brown 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: brown right_triangle at (1, 5)
Distance from target shape to cyan rectangle at (2, 1): 5
Distance from target shape to blue rectangle at (4, 3): 5
Distance from target shape to green square at (1, 3): 2
Distance from target shape to pink square at (3, 3): 4
Closest shape is the green square at (1, 3) with distance 2</think>

<answer>(1, 3)</answer>