p min 6 8 c min-cost flow problem with 6 nodes and 8 arcs n 1 10 c supply of 10 at node 1 n 6 -10 c demand of 10 at node 6 c arc list follows c arc has a 1 2 0 4 1 a 1 3 0 8 5 a 2 3 0 5 0 a 3 5 0 10 1 a 5 4 0 8 0 a 5 6 0 8 9 a 4 2 0 8 1 a 4 6 0 8 1