bbb bbc bbk bbo bby bcb bcc bck bco bcy bcz bkb bkc bkk bko bob boc bok boo boy boz by- byc byk byo byz bzo bzz c-- cbb cbc cbk cbo cby cbz ccb ccc cck cco ccz ckb ckc cko cky co- cob coc cok coo coy coz cyb cyc cyk cyo cz- czc czk czo k-z kbb kbc kbk kbo kbz kcb kcc kck kkb kkc kkk kky kob koc kok koo koy koz kyc kyo kyz kzo kzy ob- obb obc obk obo oby oc- ocb occ ock oco ocz okb okc okk oko oo- oob ooc ook ooo oyo ozo ozz ybc yby ybz ycc yco ycy ykk yob yoc yok yoo yoy yyb yyc yyy yyz yzb yzy zbb zbc zby zco zo- zob zoc zok zoo zzy zzz