What color does the clear sky have?
The sky has gray color.
    src        edge_attr  dst
0     0  to the right of    9
1     0  to the right of   17
2     0  to the right of   13
3     1   to the left of    2
4     1  to the right of    3
5     2  to the right of    3
6     2  to the right of    1
7     3   to the left of    1
8     3   to the left of    2
9     6  to the right of   13
10    6  to the right of    9
11    6  to the right of   17
12    6   to the left of   12
13    6      in front of    9
14    7  to the right of    8
15    8   to the left of    7
16    9           behind    6
17    9   to the left of    6
18    9   to the left of   14
19    9   to the left of    0
20    9   to the left of   12
21    9  to the right of   10
22    9  to the right of   17
23    9   to the left of   13
24   10   to the left of    9
25   10   to the left of   13
26   10  to the right of   15
27   10   to the left of   17
28   11               on   15
29   11   to the left of   16
30   11               on   13
31   12  to the right of    9
32   12  to the right of    6
33   12  to the right of   13
34   13   to the left of   14
35   13  to the right of   17
36   13   to the left of    0
37   13   to the left of   12
38   13   to the left of    6
39   13  to the right of    9
40   13  to the right of   10
41   14  to the right of    9
42   14  to the right of   13
43   14  to the right of   17
44   15   to the left of   10
45   15   to the left of   17
46   16               on   17
47   16  to the right of   11
48   17   to the left of    0
49   17   to the left of    9
50   17  to the right of   10
51   17   to the left of   13
52   17   to the left of    6
53   17  to the right of   15
54   17   to the left of   14