Which kind of furniture is made of wood?
The furniture is a desk.
   src        edge_attr  dst
0    0  to the right of    4
1    0   to the left of    3
2    1  to the right of    4
3    2               on    5
4    3               on    5
5    3  to the right of    0
6    4               on    5
7    4   to the left of    1
8    4   to the left of    0