* #variable= 0 #constraint= 2 #soft= 1 mincost= 1 maxcost= 1 sumcost= 1
* This is invalid according to the grammer of http://www.cril.univ-artois.fr/PB11/format.pdf ,
* but we relax the grammar to allow it.
soft: ;
[1] >= 1;
>= 0;