There are 4 shapes on a 7x7 grid. Which shape is closest to the purple 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: purple right_triangle at (2, 6)
Distance from target shape to cyan right_triangle at (5, 3): 6
Distance from target shape to pink right_triangle at (4, 3): 5
Distance from target shape to green right_triangle at (4, 1): 7
Closest shape is the pink right_triangle at (4, 3) with distance 5</think>

<answer>(4, 3)</answer>