Which color are the hills?
The hills are gray.
    src             edge_attr  dst
0     0       to the right of    7
1     0       to the right of   21
2     1                    of   21
3     1        to the left of   13
4     1       to the right of   20
5     1        to the left of   11
6     2       to the right of   20
7     3       to the right of    9
8     3       to the right of   21
9     5                    of   21
10    5       to the right of   11
11    5       to the right of   13
12    7                    of   21
13    7        to the left of    0
14    9        to the left of    3
15    9  on the other side of   18
16   11        to the left of    5
17   11       to the right of   13
18   11        to the left of   14
19   11       to the right of    1
20   11                    of   21
21   12       to the right of   19
22   12       to the right of   21
23   13       to the right of   16
24   13        to the left of   14
25   13        to the left of   11
26   13        to the left of    5
27   13       to the right of    1
28   14       to the right of   21
29   14       to the right of   13
30   14       to the right of   11
31   16        to the left of   13
32   17                beside   15
33   19        to the left of   12
34   19                    of   21
35   20        to the left of    2
36   20        to the left of    1
37   20        to the left of   21
38   21           standing on    6
39   21       to the right of   20
40   21        to the left of   14
41   21        to the left of   12
42   21        to the left of    3
43   21        to the left of    0