I left discovered that happened up .
(ROOT_0 (S_0 (ATS_3 (NP_1 (PRP_1 I)) (VP_4 (VBD_2 left) (S_2 (VP_0 (VBD_0 discovered) (SBAR_0 (S_1 (NP_0 (DT_1 that)) (VP_5 (VBD_0 happened) (PRT_0 (RP_0 up))))))))) (DOT_0 .)))