a-a a-b a-c aaa aab aac aah aak aao aar aas ab- aba abb abc abh abk abo abr abs ac- aca acb acc ach ack aco acr acs aha ahb ahc ahh ahk aho ahr ahs aka akb akc akh akk ako akr aks aoa aob aoc aoh aok aoo aor aos ar- ara arb arc arh ark aro arr ars as- asa asb asc ash ask aso asr ass baa bab bac bah bak bao bar bas bba bbb bbc bbh bbk bbo bbr bbs bca bcb bcc bch bck bco bcr bcs bha bhb bhc bhh bhk bho bhr bhs bka bkb bkc bkk bko bkr bks boa bob boc boh bok boo bor bos bra brb brh brk bro brr brs bsa bsb bsc bsh bsk bso bsr bss c-- caa cab cac cah cak cao car cas cba cbb cbc cbh cbk cbo cbr cbs cca ccb ccc cch cck cco ccr ccs ch- cha chb chc chh chk cho chr chs cka ckb ckc ckh cko cks co- coa cob coc coh cok coo cor cos cra crb crc crh crk cro crr crs csa csb csc csh csk cso csr css haa hab hac hah hak hao har has hba hbb hbc hbh hbk hbo hbr hbs hca hcb hcc hch hck hco hcr hcs hha hhb hhc hhh hhk hho hhr hhs hka hkb hkh hkk hko hkr hks hoa hob hoc hoh hok hoo hor hos hr- hra hrb hrc hrh hrk hro hrr hrs hsa hsb hsc hsh hsk hsr hss ka- kaa kab kac kah kak kao kar kas kba kbb kbc kbh kbk kbo kbr kbs kca kcb kcc kch kck kcr kcs kha khh khk kho khr khs kkb kkc kkh kkk kkr kks koa kob koc koh kok koo kor kos kra krc krk kro krr krs ksa ksb ksc ksh ksk kso ksr kss oaa oab oac oah oak oao oar oas ob- oba obb obc obh obk obo obr obs oc- oca ocb occ och ock oco ocr ocs oha ohc ohh oho ohr ohs oka okb okc okk oko okr oks oo- ooa oob ooc ooh ook ooo oor oos or- ora orb orc orh ork oro orr ors os- osa osb osc osh osk oso osr oss ra- raa rab rac rah rak rao rar ras rba rbb rbc rbh rbk rbo rbr rbs rca rcb rcc rch rco rcr rcs rh- rha rhb rhc rhh rho rhr rhs rkb rkc rkk rko rks roa rob roc roh rok roo ror ros rra rrb rrc rrh rrk rrr rrs rsa rsb rsc rsh rsk rso rsr rss saa sab sac sah sak sao sar sas sba sbb sbc sbh sbk sbo sbr sbs sca scb scc sch sck sco scr scs sh- sha shb shc shh shk sho shr shs sk- ska skb skc skh skk sko skr sks soa sob soc soh sok soo sor sos sr- sra srb src srh srk sro srr srs ss- ssa ssb ssc ssh ssk sso ssr sss