points
16
0 2 0
1 3 0
2 3 0
3 2 0
3 1 0
2 0 0
1 0 0
0 1 0

0 -2 0
1 -3 0
2 -3 0
3 -2 0
3 -1 0
2 0 0
1 0 0
0 -1 0
end points
lines
16
0 1
1 2
2 3
3 4
4 5
5 6
6 7
7 0

8 9
9 10
10 11
11 12
12 13
13 14
14 15
15 8
end lines