The boy piled <apostrophe>s up the friend .
(ROOT_0 (S_0 (ATS_3 (NP_1 (DT_1 The) (NN_2 boy)) (VP_4 (VBD_2 piled) (S_2 (VP_0 (ATVP_1 (VBZ_0 <apostrophe>s) (PRT_0 (RP_0 up))) (NP_5 (DT_0 the) (NN_2 friend)))))) (DOT_0 .)))