number of vertices :   16
number of required edges         4
2 6 1 1 3
3 7 1 1 1
4 8 1 1 2
9 10 1 1 3
number of non required edges        20
1 2 1 1 0
1 5 1 1 0
2 3 1 1 0
3 4 1 1 0
5 6 1 1 0
5 9 1 1 0
6 7 1 1 0
6 10 1 1 0
7 8 1 1 0
7 11 1 1 0
8 12 1 1 0
9 13 1 1 0
10 11 1 1 0
10 14 1 1 0
11 12 1 1 0
11 15 1 1 0
12 16 1 1 0
13 14 1 1 0
14 15 1 1 0
15 16 1 1 0

