There are 3 shapes on a 9x9 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 (6, 4)
Distance from target shape to brown square at (1, 2): 7
Distance from target shape to blue square at (7, 3): 2
Closest shape is the blue square at (7, 3) with distance 2</think>

<answer>(7, 3)</answer>