a-a a-b aaa aab aak aam aao aar ab- aba abb abk abm abo abr aka akb akk akm ako akr ama amb amk amm amo amr aoa aob aok aom aoo aor ar- ara arb ark arm aro arr baa bab bak bam bao bar bba bbb bbk bbm bbo bbr bka bkb bkk bkm bko bkr bma bmb bmk bmm bmo bmr boa bob bok bom boo bor bra brb brk brm bro brr ka- kaa kab kak kam kao kar kba kbb kbk kbm kbo kbr kkb kkk kkm kkr kma kmb kmk kmm kmo koa kob kok kom koo kor kra krk kro krr m-o m-r maa mab mak mam mao mar mba mbb mbk mbm mbo mbr mka mkb mkk mkm mko mkr mma mmb mmk mmm mmo mmr moa mob mok mom moo mor mra mrb mrk mrm mro mrr oaa oab oak oam oao oar ob- oba obb obk obm obo obr oka okb okk oko okr om- oma omb omm omo omr oo- ooa oob ook oom ooo oor or- ora orb ork orm oro orr ra- raa rab rak ram rao rar rba rbb rbk rbm rbo rbr rkb rkk rkm rko rma rmb rmm rmo rmr roa rob rok rom roo ror rra rrb rrk rrm rrr