a-a a-b a-c aaa aab aac aah aak aao aas ab- aba abb abc abh abk abo abs ac- aca acb acc ach ack aco acs aha ahb ahc ahh ahk aho ahs aka akb akc akh akk ako aks aoa aob aoc aoh aok aoo aos as- asa asb asc ash ask aso ass baa bab bac bah bak bao bas bba bbb bbc bbh bbk bbo bbs bca bcb bcc bch bck bco bcs bha bhb bhc bhh bhk bho bhs bka bkb bkc bkk bko bks boa bob boc boh bok boo bos bsa bsb bsc bsh bsk bso bss c-- caa cab cac cah cak cao cas cba cbb cbc cbh cbk cbo cbs cca ccb ccc cch cck cco ccs ch- cha chb chc chh chk cho chs cka ckb ckc ckh cko cks co- coa cob coc coh cok coo cos csa csb csc csh csk cso css haa hab hac hah hak hao has hba hbb hbc hbh hbk hbo hbs hca hcb hcc hch hck hco hcs hha hhb hhc hhh hhk hho hhs hka hkb hkh hkk hko hks hoa hob hoc hoh hok hoo hos hsa hsb hsc hsh hsk hss ka- kaa kab kac kah kak kao kas kba kbb kbc kbh kbk kbo kbs kca kcb kcc kch kck kcs kha khh khk kho khs kkb kkc kkh kkk kks koa kob koc koh kok koo kos ksa ksb ksc ksh ksk kso kss oaa oab oac oah oak oao oas ob- oba obb obc obh obk obo obs oc- oca ocb occ och ock oco ocs oha ohc ohh oho ohs oka okb okc okk oko oks oo- ooa oob ooc ooh ook ooo oos os- osa osb osc osh osk oso oss saa sab sac sah sak sao sas sba sbb sbc sbh sbk sbo sbs sca scb scc sch sck sco scs sh- sha shb shc shh shk sho shs sk- ska skb skc skh skk sko sks soa sob soc soh sok soo sos ss- ssa ssb ssc ssh ssk sso sss