a-a a-b aaa aab aaf aam aan aao aar ab- aba abb abf abm abn abo abr af- afa afb aff afm afn afo afr ama amb amf amm amn amo amr an- ana anb anf anm ann ano anr aoa aob aof aom aon aoo aor ar- ara arb arf arm arn aro arr baa bab baf bam ban bao bar bba bbb bbf bbm bbn bbo bbr bfa bfb bff bfm bfn bfo bfr bma bmb bmf bmm bmn bmo bmr bna bnb bnf bnn bno bnr boa bob bof bom bon boo bor bra brb brf brm brn bro brr faa fab faf fam fan fao far fba fbb fbf fbm fbn fbo fbr ffa fff ffm ffn ffo ffr fma fmb fmf fmm fmn fmo fmr fna fnb fnf fnm fnn fnr foa fob fof fom fon foo for fra frb frf frm frn fro frr m-f m-o m-r maa mab maf mam man mao mar mba mbb mbf mbm mbo mbr mfa mfb mff mfm mfn mfo mfr mma mmb mmf mmm mmn mmo mmr mna mnb mnf mnm mnn mno mnr moa mob mof mom mon moo mor mra mrb mrf mrm mrn mro mrr naa nab naf nam nan nao nar nba nbb nbf nbm nbn nbo nbr nfa nfb nff nfn nfo nfr nma nmb nmm nmn nmo nmr nna nnb nnf nnm nnn nno no- noa nob nof nom non noo nor nra nrb nrf nrm nrn nro nrr oaa oab oaf oam oan oao oar ob- oba obb obf obm obn obo obr of- ofa ofb off ofm ofn ofo ofr om- oma omb omf omm omn omo omr on- ona onb onf onn ono onr oo- ooa oob oof oom oon ooo oor or- ora orb orf orm orn oro orr ra- raa rab raf ram ran rao rar rba rbb rbf rbm rbn rbo rbr rfa rfb rff rfm rfn rfo rfr rma rmb rmf rmm rmn rmo rmr rna rnb rnm rnn rno rnr roa rob rof rom ron roo ror rra rrb rrf rrm rrn rrr