sort the bad guys from the good , which is its essential problem 
(ROOT (S (S (VP (VB sort) (NP (DT the) (JJ bad) (NNS guys)) (PP (IN from) (NP (DT the) (NN good))))) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (PRP$ its) (JJ essential) (NN problem)))))))
(ROOT (S (S (VP (VB ) (NP (DT ) (JJ ) (NNS )) (PP (IN ) (NP (DT ) (NN ))))) (, ) (SBAR (WHNP (WDT )) (S (VP (VBZ ) (NP (PRP$ ) (JJ ) (NN )))))))