a-a a-b aaa aab aaf aam aao aar ab- aba abb abf abm abo abr af- afa afb aff afm afo afr ama amb amf amm amo amr aoa aob aof aom aoo aor ar- ara arb arf arm aro arr baa bab baf bam bao bar bba bbb bbf bbm bbo bbr bfa bfb bff bfm bfo bfr bma bmb bmf bmm bmo bmr boa bob bof bom boo bor bra brb brf brm bro brr faa fab faf fam fao far fba fbb fbf fbm fbo fbr ffa fff ffm ffo ffr fma fmb fmf fmm fmo fmr foa fob fof fom foo for fra frb frf frm fro frr m-f m-o m-r maa mab maf mam mao mar mba mbb mbf mbm mbo mbr mfa mfb mff mfm mfo mfr mma mmb mmf mmm mmo mmr moa mob mof mom moo mor mra mrb mrf mrm mro mrr oaa oab oaf oam oao oar ob- oba obb obf obm obo obr of- ofa ofb off ofm ofo ofr om- oma omb omf omm omo omr oo- ooa oob oof oom ooo oor or- ora orb orf orm oro orr ra- raa rab raf ram rao rar rba rbb rbf rbm rbo rbr rfa rfb rff rfm rfo rfr rma rmb rmf rmm rmo rmr roa rob rof rom roo ror rra rrb rrf rrm rrr