a-a a-b aaa aab aam aan aao aar ab- aba abb abm abn abo abr ama amb amm amn amo amr an- ana anb anm ann ano anr aoa aob aom aon aoo aor ar- ara arb arm arn aro arr baa bab bam ban bao bar bba bbb bbm bbn bbo bbr bma bmb bmm bmn bmo bmr bna bnb bnn bno bnr boa bob bom bon boo bor bra brb brm brn bro brr m-o m-r maa mab mam man mao mar mba mbb mbm mbo mbr mma mmb mmm mmn mmo mmr mna mnb mnm mnn mno mnr moa mob mom mon moo mor mra mrb mrm mrn mro mrr naa nab nam nan nao nar nba nbb nbm nbn nbo nbr nma nmb nmm nmn nmo nmr nna nnb nnm nnn nno no- noa nob nom non noo nor nra nrb nrm nrn nro nrr oaa oab oam oan oao oar ob- oba obb obm obn obo obr om- oma omb omm omn omo omr on- ona onb onn ono onr oo- ooa oob oom oon ooo oor or- ora orb orm orn oro orr ra- raa rab ram ran rao rar rba rbb rbm rbn rbo rbr rma rmb rmm rmn rmo rmr rna rnb rnm rnn rno rnr roa rob rom ron roo ror rra rrb rrm rrn rrr