There are 4 shapes on a 7x7 grid. Which shape is closest to the green 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: green right_triangle at (1, 5)
Distance from target shape to gray square at (0, 1): 5
Distance from target shape to brown rectangle at (3, 3): 4
Distance from target shape to cyan trapezoid at (6, 4): 6
Closest shape is the brown rectangle at (3, 3) with distance 4</think>

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