What kind of vehicle is brown?
The vehicle is a train.
    src        edge_attr  dst
0     0   to the left of    2
1     0   to the left of    5
2     1  to the right of    4
3     1  to the right of    3
4     2  to the right of    0
5     3   to the left of    5
6     3   to the left of    1
7     4               on    3
8     4   to the left of    1
9     4   to the left of    5
10    5  to the right of    4
11    5  to the right of    0
12    5  to the right of    3