himself piled it have to a boulders .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_0 himself)) (VP_4 (VBD_2 piled) (S_2 (NP_0 (PRP_1 it)) (VP_5 (VBP_0 have) (PP_2 (TO_0 to) (NP_2 (DT_0 a) (NNS_1 boulders))))))) (DOT_0 .)))