c

 c        This is a simple example file to demonstrate the

 c     DIMACS input file format for minimum-cost flow problems.

 c 

 c problem line :

 p min 4 5

 c

 c node descriptor lines :

 n 1 4

 n 4 -4

 c

 c arc descriptor lines :

 a 1 2 0 4 2

 a 1 3 0 2 2

 a 2 3 0 2 1

 a 2 4 0 3 3

 a 3 4 0 5 1