Volcanic Eruptions

6
7 4
-1 -1 -1 1 1 1 -1
2 1
3 2
4 3
5 4
6 5
7 6
8 2
-1 1 1 1 1 -1 1 1
2 1
6 2
8 6
3 8
7 3
5 7
4 5
8 2
-1 1 -1 -1 -1 1 -1 -1
2 1
8 2
4 1
5 4
3 4
7 2
6 8
8 4
1 1 1 1 1 -1 1 -1
8 1
3 1
4 3
5 4
6 4
7 6
2 5
8 4
1 1 1 1 -1 -1 1 1
2 1
5 1
4 5
8 5
3 8
7 2
6 2
18 10
-1 -1 -1 -1 -1 -1 -1 -1 -1 1 -1 1 1 -1 1 1 1 1
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
11 12
12 13
9 14
14 15
15 16
16 17
17 18