What is the ceiling made of?
The ceiling is made of wood.
    src        edge_attr  dst
0     0  to the right of   14
1     2   to the left of   16
2     2               on    3
3     3  to the right of    4
4     3   to the left of   12
5     3   to the left of   16
6     4   to the left of    3
7     5  to the right of   14
8     6               on    5
9     8      in front of    9
10    8   to the left of   16
11    8   to the left of   11
12    8   to the left of    9
13    9  to the right of    8
14    9   to the left of   16
15    9           behind    8
16    9   to the left of   10
17   10   to the left of   15
18   10  to the right of   12
19   10  to the right of    9
20   11  to the right of    8
21   11   to the left of   16
22   12   to the left of   10
23   12  to the right of    3
24   12   to the left of   16
25   13  to the right of   17
26   14   to the left of    5
27   14  to the right of   17
28   14   to the left of    0
29   15  to the right of   16
30   15  to the right of   10
31   16   to the left of   15
32   16  to the right of    8
33   16  to the right of    9
34   16  to the right of   12
35   16  to the right of   11
36   16  to the right of    3
37   16  to the right of    2
38   17   to the left of   13
39   17   to the left of   14