set K := 1 2 3;
set NODES := 1 2 3;
set ARCS := (1,2) (1,3) 
            (2,1) (2,3)
            (3,1) (3,2);


param b :=
# i   k		b[i,k]
  1   1		0
  1   2		1
  1   3		-1
  2   1		-1
  2   2		0
  2   3		1
  3   1		1
  3   2		-1
  3   3		0;



param U :=
1 2 1
2 3 1
3 1 1;

param c :=
# i j k	 c[i,j,k]
  1 3 1  1
  1 3 2  1
  1 3 3	 1
  2 1 1  1
  2 1 2  1
  2 1 3  1
  3 2 1  1
  3 2 2  1
  3 2 3  1;