What is the color of the plane that is in front of the building?
The plane is gray.
    src        edge_attr  dst
0     0   to the left of    9
1     2           behind    9
2     3               of    9
3     3   to the left of    7
4     4               of    9
5     4  to the right of    7
6     7  to the right of    3
7     7   to the left of    4
8     7               on    9
9     8  to the right of   12
10    8   to the left of   10
11    9  to the right of    0
12    9      in front of    2
13   10  to the right of    8
14   10  to the right of   12
15   10  to the right of   14
16   11  to the right of   12
17   12               of    9
18   12   to the left of   14
19   12   to the left of   11
20   12   to the left of    8
21   12   to the left of   10
22   14   to the left of   10
23   14  to the right of   12
24   14       sitting in    8