There are 4 shapes on a 7x7 grid. Which shape is closest to the blue 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: blue right_triangle at (5, 4)
Distance from target shape to yellow trapezoid at (2, 3): 4
Distance from target shape to orange right_triangle at (2, 1): 6
Distance from target shape to brown rectangle at (6, 3): 2
Closest shape is the brown rectangle at (6, 3) with distance 2</think>

<answer>(6, 3)</answer>