c Test Graph
c 6 vertices and 9 edges
p max 6 9
n 1 s
n 6 t
a 1 2 15
a 1 3 20
a 2 3 9
a 2 4 5
a 2 5 8
a 3 4 7
a 3 5 10
a 4 6 22
a 5 6 6