houses of a sharp boulders the group , <apostrophe><apostrophe>
(ROOT_0 (S_0 (ATS_2 (PP_2 (ATPP_0 (ATPP_0 (NP_4 (NNS_1 houses)) (IN_1 of)) (NP_5 (ATNP_1 (DT_0 a) (JJ_1 sharp)) (NNS_1 boulders))) (NP_5 (DT_0 the) (NN_2 group))) (COMMA_0 ,)) (APOSTROPHE_0 <apostrophe><apostrophe>)))