a masterful work of art of their own 
(ROOT (NP (NP (DT a) (JJ masterful) (NN work)) (PP (IN of) (NP (NN art))) (PP (IN of) (NP (PRP$ their) (JJ own)))))
(ROOT (NP (NP (DT ) (JJ ) (NN )) (PP (IN ) (NP (NN ))) (PP (IN ) (NP (PRP$ ) (JJ )))))