To use this checker, just execute the checker in a terminal console:
./checker.sh EXITCODE INSTANCE < WITNESS

Given a WITNESS (answer set) as a set of facts on a single line
the checker will assess whether this represents an optimal answer set for an INSTANCE, or not.
Additionally, the EXITCODE of the solver is provided, for details see the specification at

https://www.mat.unical.it/aspcomp2014/ProblemIOSpecification

An example call for the checker would be
	./checker.sh 10 instance.asp < rightSolution1.txt
which returns OK on stdout and exits with code 0.

On the other hand, a wrong witness is rejected. For example
	./checker.sh 10 instance.asp < wrongSolution1.txt
returns FAIL on stdout and exits with code 1.

