Sample data from the documentation (except reverse_cost is 2)

sampledata.data

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