There are 4 shapes on a 8x8 grid. Which shape is closest to the gray 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: gray right_triangle at (4, 2)
Distance from target shape to cyan right_triangle at (1, 6): 7
Distance from target shape to red trapezoid at (0, 7): 9
Distance from target shape to yellow square at (6, 4): 4
Closest shape is the yellow square at (6, 4) with distance 4</think>

<answer>(6, 4)</answer>