What is located on top of the table?
The papers are on top of the table.
    src        edge_attr  dst
0     0        on top of    2
1     0   to the left of    3
2     1   to the left of    3
3     2   to the left of    9
4     3  to the right of    1
5     3  to the right of   10
6     3  to the right of    0
7     3  to the right of    8
8     3  to the right of   13
9     3  to the right of    4
10    4   to the left of    3
11    4   to the left of   13
12    5  to the right of   14
13    5  to the right of    7
14    5               on    3
15    7               on    9
16    7   to the left of    5
17    8   to the left of   13
18    8   to the left of    3
19    9  to the right of    2
20   10   to the left of    3
21   13   to the left of    3
22   13  to the right of    4
23   13  to the right of    8
24   14   to the left of    5