Where are the bricks?
The bricks are on the walkway.
    src        edge_attr  dst
0     0   to the left of    5
1     0  to the right of   18
2     0   to the left of   10
3     1   to the left of   13
4     1   to the left of   18
5     1   to the left of    3
6     1   to the left of    9
7     2   to the left of    5
8     2               on   15
9     2   to the left of   11
10    2   to the left of   16
11    3  to the right of    1
12    3  to the right of   14
13    3   to the left of    6
14    3  to the right of    4
15    3   to the left of    8
16    3   to the left of    7
17    4   to the left of    3
18    4               on    1
19    5  to the right of    2
20    5  to the right of   15
21    5  to the right of   17
22    5  to the right of    0
23    6  to the right of    3
24    6   to the left of    7
25    6  to the right of   12
26    7  to the right of    6
27    7               by    3
28    7  to the right of    3
29    8  to the right of    3
30    8  to the right of   12
31    9  to the right of   14
32    9  to the right of    1
33   10  to the right of    0
34   11  to the right of    2
35   12   to the left of    6
36   12   to the left of    8
37   13  to the right of    1
38   13               on    9
39   13  to the right of   14
40   14   to the left of    9
41   14   to the left of   13
42   14   to the left of    3
43   15   to the left of    5
44   15   to the left of   16
45   16  to the right of    2
46   16  to the right of   15
47   17   to the left of    5
48   17               on    0
49   18   to the left of    0
50   18  to the right of    1
51   18               by    3