the three leads produce adequate performances , but 
(ROOT (S (S (NP (DT the) (CD three) (NNS leads)) (VP (VBP produce) (NP (JJ adequate) (NNS performances)))) (, ,) (CC but)))
(ROOT (S (S (NP (DT ) (CD ) (NNS )) (VP (VBP ) (NP (JJ ) (NNS )))) (, ) (CC )))