The ladder is on what?
The ladder is on the fire truck.
    src        edge_attr  dst
0     0        on top of    2
1     0  to the right of   12
2     0               on    2
3     0  to the right of    9
4     0   to the left of    7
5     1      in front of    7
6     1  to the right of    2
7     2      in front of    7
8     2        on top of    8
9     2       driving on    8
10    2   to the left of    7
11    2  to the right of    9
12    2  to the right of   12
13    2  to the right of   13
14    2           behind   11
15    2               on    8
16    2   to the left of    1
17    2   to the left of    3
18    3  to the right of    4
19    3  to the right of    2
20    3  to the right of    9
21    3  to the right of   10
22    4  to the right of    5
23    4   to the left of    3
24    4  to the right of    9
25    5               on    9
26    5   to the left of   10
27    5   to the left of    4
28    6   to the left of    8
29    6          next to    8
30    6             near    8
31    7  to the right of    2
32    7       driving on    8
33    7  to the right of    0
34    7           behind    2
35    8             near    6
36    8  to the right of    6
37    9   to the left of    2
38    9   to the left of    3
39    9   to the left of    0
40    9   to the left of    4
41   10   to the left of    3
42   10  to the right of    5
43   11  to the right of   13
44   11   to the left of   14
45   12   to the left of    0
46   12   to the left of    2
47   13   to the left of   11
48   13   to the left of    2
49   13   on the side of    8
50   14  to the right of   11
51   14   on the back of    2