a-a a-b a-c aaa aab aac aak aam aao aar ab- aba abb abc abk abm abo abr ac- aca acb acc ack acm aco acr aka akb akc akk akm ako akr ama amb amc amk amm amo amr aoa aob aoc aok aom aoo aor ar- ara arb arc ark arm aro arr baa bab bac bak bam bao bar bba bbb bbc bbk bbm bbo bbr bca bcb bcc bck bcm bco bcr bka bkb bkc bkk bkm bko bkr bma bmb bmc bmk bmm bmo bmr boa bob boc bok bom boo bor bra brb brk brm bro brr c-- caa cab cac cak cam cao car cba cbb cbc cbk cbm cbo cbr cca ccb ccc cck ccm cco ccr cka ckb ckc ckm cko cma cmb cmc cmk cmm cmo cmr co- coa cob coc cok com coo cor cra crb crc crk crm cro crr ka- kaa kab kac kak kam kao kar kba kbb kbc kbk kbm kbo kbr kca kcb kcc kck kcm kcr kkb kkc kkk kkm kkr kma kmb kmc kmk kmm kmo koa kob koc kok kom koo kor kra krc krk kro krr m-o m-r maa mab mac mak mam mao mar mba mbb mbc mbk mbm mbo mbr mc- mca mcb mcc mck mcm mco mcr mka mkb mkc mkk mkm mko mkr mma mmb mmc mmk mmm mmo mmr moa mob moc mok mom moo mor mra mrb mrc mrk mrm mro mrr oaa oab oac oak oam oao oar ob- oba obb obc obk obm obo obr oc- oca ocb occ ock ocm oco ocr oka okb okc okk oko okr om- oma omb omc omm omo omr oo- ooa oob ooc ook oom ooo oor or- ora orb orc ork orm oro orr ra- raa rab rac rak ram rao rar rba rbb rbc rbk rbm rbo rbr rca rcb rcc rcm rco rcr rkb rkc rkk rkm rko rma rmb rmc rmm rmo rmr roa rob roc rok rom roo ror rra rrb rrc rrk rrm rrr