b-p bbb bbc bbd bbo bbp bcb bcc bcd bco bcp bdb bdc bdd bdo bdp bob boc bod boo bop bpb bpc bpd bpo bpp c-- cbb cbc cbd cbo cbp ccb ccc ccd cco ccp cdb cdc cdd cdo cdp co- cob coc cod coo cop cpb cpc cpd cpo cpp dbb dbc dbd dbo dbp dcb dcc dcd dco dcp ddb ddc ddd ddo ddp dob doc dod doo dop dpb dpc dpd dpo dpp ob- obb obc obd obo obp oc- ocb occ ocd oco ocp odb odc odd odo odp oo- oob ooc ood ooo oop op- opb opc opd opo opp p-p pbb pbc pbd pbo pbp pcb pcc pcd pco pcp pdb pdc pdd pdo pdp pob poc pod poo pop ppb ppc ppd ppo ppp