There are 3 shapes on a 8x8 grid. Which shape is closest to the blue rectangle 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 rectangle at (7, 4)
Distance from target shape to gray right_triangle at (5, 2): 4
Distance from target shape to yellow right_triangle at (2, 4): 5
Closest shape is the gray right_triangle at (5, 2) with distance 4</think>

<answer>(5, 2)</answer>