1 c HUGO max flow problem
2 p max 7 9
3 n 1 s
4 n 7 t
5 a 1 2 3
6 a 1 3 2
7 a 1 4 1
8 a 2 5 3
9 a 3 5 2
10 a 3 7 5
11 a 3 6 3
12 a 4 6 1
13 a 5 7 2
14 a 6 7 4