a-a a-b a-c aaa aab aac aak aam aao aar aas ab- aba abb abc abk abm abo abr abs ac- aca acb acc ack acm aco acr acs aka akb akc akk akm ako akr aks ama amb amc amk amm amo amr ams aoa aob aoc aok aom aoo aor aos ar- ara arb arc ark arm aro arr ars as- asa asb asc ask asm aso asr ass baa bab bac bak bam bao bar bas bba bbb bbc bbk bbm bbo bbr bbs bca bcb bcc bck bcm bco bcr bcs bka bkb bkc bkk bkm bko bkr bks bma bmb bmc bmk bmm bmo bmr bms boa bob boc bok bom boo bor bos bra brb brk brm bro brr brs bsa bsb bsc bsk bsm bso bsr bss c-- caa cab cac cak cam cao car cas cba cbb cbc cbk cbm cbo cbr cbs cca ccb ccc cck ccm cco ccr ccs cka ckb ckc ckm cko cks cma cmb cmc cmk cmm cmo cmr cms co- coa cob coc cok com coo cor cos cra crb crc crk crm cro crr crs csa csb csc csk csm cso csr css ka- kaa kab kac kak kam kao kar kas kba kbb kbc kbk kbm kbo kbr kbs kca kcb kcc kck kcm kcr kcs kkb kkc kkk kkm kkr kks kma kmb kmc kmk kmm kmo kms koa kob koc kok kom koo kor kos kra krc krk kro krr krs ksa ksb ksc ksk ksm kso ksr kss m-o m-r maa mab mac mak mam mao mar mas mba mbb mbc mbk mbm mbo mbr mbs mc- mca mcb mcc mck mcm mco mcr mcs mka mkb mkc mkk mkm mko mkr mks mma mmb mmc mmk mmm mmo mmr mms moa mob moc mok mom moo mor mos mra mrb mrc mrk mrm mro mrr mrs msa msb msc msk msm mso msr mss oaa oab oac oak oam oao oar oas ob- oba obb obc obk obm obo obr obs oc- oca ocb occ ock ocm oco ocr ocs oka okb okc okk oko okr oks om- oma omb omc omm omo omr oms oo- ooa oob ooc ook oom ooo oor oos or- ora orb orc ork orm oro orr ors os- osa osb osc osk osm oso osr oss ra- raa rab rac rak ram rao rar ras rba rbb rbc rbk rbm rbo rbr rbs rca rcb rcc rcm rco rcr rcs rkb rkc rkk rkm rko rks rma rmb rmc rmm rmo rmr rms roa rob roc rok rom roo ror ros rra rrb rrc rrk rrm rrr rrs rsa rsb rsc rsk rsm rso rsr rss saa sab sac sak sam sao sar sas sba sbb sbc sbk sbm sbo sbr sbs sca scb scc sck scm sco scr scs sk- ska skb skc skk skm sko skr sks sma smb smc smk smm smo smr sms soa sob soc sok som soo sor sos sr- sra srb src srk srm sro srr srs ss- ssa ssb ssc ssk ssm sso ssr sss