Who is riding on a train?
The man is riding on a train.
    src        edge_attr  dst
0     0  to the right of    9
1     0       sitting on    2
2     0      standing on    2
3     1   to the left of   12
4     3               on    2
5     4   to the left of    8
6     4  to the right of   11
7     5  to the right of    6
8     6   to the left of    5
9     6   to the left of   11
10    6   to the left of   10
11    8  to the right of    4
12    9   to the left of    0
13   10       working on    1
14   10      standing on    1
15   10          wearing    5
16   10        on top of    1
17   10   to the left of   13
18   10  to the right of    6
19   10        riding on    1
20   11  to the right of    6
21   11   to the left of   13
22   11   to the left of    4
23   12  to the right of    1
24   12  to the right of   13
25   13   to the left of   12
26   13  to the right of   10
27   13  to the right of   11