Which kind of vegetable is on the pizza?
The vegetable is an olive.
    src        edge_attr  dst
0     0  to the right of    2
1     0  to the right of    1
2     0  to the right of    5
3     0  to the right of    6
4     1   to the left of    0
5     1  to the right of    7
6     2  to the right of   11
7     2  to the right of    6
8     2   to the left of    0
9     3               by   18
10    4               on   18
11    4  to the right of   15
12    4   to the left of   12
13    5   to the left of    0
14    5  to the right of    7
15    6               on   18
16    6   to the left of    2
17    6  to the right of   13
18    6   to the left of    0
19    6   to the left of   11
20    7   to the left of    5
21    7   to the left of    1
22    8               on   18
23   11   to the left of    2
24   11  to the right of    6
25   11  to the right of   13
26   12  to the right of    4
27   12               on   18
28   13   to the left of    6
29   13               on   18
30   13   to the left of   11
31   14               on   18
32   14  to the right of   19
33   15   to the left of    4
34   16   to the left of   19
35   16   to the left of   17
36   17  to the right of   16
37   17               on   18
38   17  to the right of   19
39   18             with    6
40   18             with   12
41   18             with    4
42   18             with   14
43   19   to the left of   14
44   19  to the right of   16
45   19   to the left of   17