There are 3 shapes on a 8x8 grid. Which shape is closest to the red 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: red rectangle at (7, 7)
Distance from target shape to gray right_triangle at (1, 3): 10
Distance from target shape to green trapezoid at (1, 0): 13
Closest shape is the gray right_triangle at (1, 3) with distance 10</think>

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