on the strength of their own cleverness 
(ROOT (PP (IN on) (NP (NP (DT the) (NN strength)) (PP (IN of) (NP (PRP$ their) (JJ own) (NN cleverness))))))
(ROOT (PP (IN ) (NP (NP (DT ) (NN )) (PP (IN ) (NP (PRP$ ) (JJ ) (NN ))))))