a-a a-b aaa aab aaf aak aam aao aar ab- aba abb abf abk abm abo abr af- afa afb aff afk afm afo afr aka akb akk akm ako akr ama amb amf amk amm amo amr aoa aob aof aok aom aoo aor ar- ara arb arf ark arm aro arr baa bab baf bak bam bao bar bba bbb bbf bbk bbm bbo bbr bfa bfb bff bfm bfo bfr bka bkb bkf bkk bkm bko bkr bma bmb bmf bmk bmm bmo bmr boa bob bof bok bom boo bor bra brb brf brk brm bro brr faa fab faf fak fam fao far fba fbb fbf fbk fbm fbo fbr ffa fff ffk ffm ffo ffr fka fkb fkf fkk fkm fma fmb fmf fmm fmo fmr foa fob fof fok fom foo for fra frb frf frk frm fro frr ka- kaa kab kaf kak kam kao kar kba kbb kbf kbk kbm kbo kbr kfa kff kfm kfo kkb kkk kkm kkr kma kmb kmf kmk kmm kmo koa kob kof kok kom koo kor kra krf krk kro krr m-f m-o m-r maa mab maf mak mam mao mar mba mbb mbf mbk mbm mbo mbr mfa mfb mff mfm mfo mfr mka mkb mkk mkm mko mkr mma mmb mmf mmk mmm mmo mmr moa mob mof mok mom moo mor mra mrb mrf mrk mrm mro mrr oaa oab oaf oak oam oao oar ob- oba obb obf obk obm obo obr of- ofa ofb off ofm ofo ofr oka okb okk oko okr om- oma omb omf omm omo omr oo- ooa oob oof ook oom ooo oor or- ora orb orf ork orm oro orr ra- raa rab raf rak ram rao rar rba rbb rbf rbk rbm rbo rbr rfa rfb rff rfk rfm rfo rfr rkb rkf rkk rkm rko rma rmb rmf rmm rmo rmr roa rob rof rok rom roo ror rra rrb rrf rrk rrm rrr