Which color do the animals the rocks are behind of have?
The bears have brown color.
    src        edge_attr  dst
0     0               of    7
1     1   to the left of    4
2     2               of    7
3     2  to the right of    6
4     2   to the left of    8
5     3  to the right of    6
6     4           behind    7
7     4  to the right of    1
8     5               of    7
9     6   to the left of    2
10    6   to the left of    3
11    7               on    9
12    7      in front of    8
13    7      in front of    4
14    8  to the right of    2
15    8           behind    7