but it 's worth the concentration . 
(ROOT (S (CC but) (NP (PRP it)) (VP (VBZ 's) (ADJP (JJ worth) (NP (DT the) (NN concentration)))) (. .)))
(ROOT (S (CC ) (NP (PRP )) (VP (VBZ ) (ADJP (JJ ) (NP (DT ) (NN )))) (. )))