Which kind of vehicle is in front of the building?
The vehicle is a truck.
    src        edge_attr  dst
0     1   to the left of   21
1     1  to the right of   10
2     1   to the left of    5
3     1   to the left of   19
4     1  to the right of   17
5     2   to the left of    5
6     2   to the left of   21
7     2  to the right of   17
8     2  to the right of   10
9     2  to the right of   20
10    2   to the left of   19
11    3           behind    5
12    4   to the left of   23
13    4   to the left of   15
14    5      in front of    3
15    5      in front of   16
16    5  to the right of    2
17    5  to the right of   12
18    5   to the left of    9
19    5   to the left of   22
20    5  to the right of   21
21    5  to the right of    1
22    8               on   16
23    9  to the right of    5
24   10   to the left of   12
25   10   to the left of    1
26   10   to the left of    2
27   11   to the left of   15
28   11   to the left of   23
29   12   to the left of    5
30   12  to the right of   17
31   12  to the right of   10
32   12  to the right of   20
33   12   to the left of   19
34   12   to the left of   21
35   15  to the right of   11
36   15  to the right of    4
37   16           behind    5
38   17   to the left of   12
39   17   to the left of    2
40   17   to the left of    1
41   19  to the right of   12
42   19  to the right of    2
43   19  to the right of    1
44   19  to the right of   21
45   20   to the left of   12
46   20   to the left of    2
47   21  to the right of    1
48   21   to the left of    5
49   21   to the left of   19
50   21  to the right of    2
51   21  to the right of   12
52   22  to the right of    5
53   22          wearing    9
54   23  to the right of    4
55   23  to the right of   11