c This is a sample maxflow problem
c from Lawler's "Combinatorial Optimization" book,
c Page 111, figure 4.3
c
c value
s 4
c arc flows
a 1 2 2
a 1 3 2
a 2 4 2
a 3 2 0
a 3 5 2
a 4 3 0
a 4 6 2
a 5 4 0
a 5 6 2