What is the color of the foggy sky?
The sky is gray.
   src        edge_attr  dst
0    3  to the right of   13
1    3  to the right of    5
2    5   to the left of    3
3    6   to the left of   10
4    7  to the right of    8
5    8   to the left of    7
6   10  to the right of    6
7   13   to the left of    3