What are the vegetables on the pizza?
The vegetables are olives.
    src edge_attr  dst
0     2        on    6
1     3        on    6
2     4        on    5
3     5        on    6
4     5        on    5
5     5      with    4
6     5      with    5
7     5      with   11
8     5      with    9
9     7        of    7
10    9        on    5
11   10        of    7
12   11        on    5