Which material is the fence made of?
The fence is made of wood.
    src        edge_attr  dst
0     0             near    2
1     0           behind    2
2     0      in front of    1
3     0               by    1
4     0          holding    5
5     0   to the left of    3
6     1           behind    0
7     2           around    0
8     2             near    0
9     2      in front of    0
10    3  to the right of   11
11    3  to the right of    7
12    3  to the right of   12
13    3  to the right of    0
14    6  to the right of   13
15    6               by    1
16    7   to the left of    3
17    7  to the right of   13
18    7  to the right of   14
19   10               by    2
20   11  to the right of   13
21   11  to the right of   14
22   11   to the left of    3
23   12   to the left of    3
24   12               of    0
25   13   to the left of   11
26   13   to the left of   14
27   13   to the left of    6
28   13   to the left of    7
29   14   to the left of    7
30   14   to the left of   11
31   14  to the right of   13