a-a a-b a-t aaa aab aaf aam aao aar aat ab- aba abb abf abm abo abr abt af- afa afb aff afm afo afr aft ama amb amf amm amo amr amt aoa aob aof aom aoo aor aot ar- ara arb arf arm aro arr art at- ata atb atf atm ato atr att baa bab baf bam bao bar bat bba bbb bbf bbm bbo bbr bbt bfa bfb bff bfm bfo bfr bft bma bmb bmf bmm bmo bmr bmt boa bob bof bom boo bor bot bra brb brf brm bro brr brt bta btb btf btm bto btr btt faa fab faf fam fao far fat fba fbb fbf fbm fbo fbr fbt ffa fff ffm ffo ffr fft fma fmb fmf fmm fmo fmr fmt foa fob fof fom foo for fot fra frb frf frm fro frr frt fta ftb ftf ftm fto ftr ftt m-f m-o m-r maa mab maf mam mao mar mat mba mbb mbf mbm mbo mbr mbt mfa mfb mff mfm mfo mfr mft mma mmb mmf mmm mmo mmr mmt moa mob mof mom moo mor mot mra mrb mrf mrm mro mrr mrt mta mtb mtf mtm mto mtr mtt oaa oab oaf oam oao oar oat ob- oba obb obf obm obo obr obt of- ofa ofb off ofm ofo ofr oft om- oma omb omf omm omo omr omt oo- ooa oob oof oom ooo oor oot or- ora orb orf orm oro orr ort ot- ota otb otf otm oto otr ott ra- raa rab raf ram rao rar rat rba rbb rbf rbm rbo rbr rbt rfa rfb rff rfm rfo rfr rft rma rmb rmf rmm rmo rmr rmt roa rob rof rom roo ror rot rra rrb rrf rrm rrr rrt rta rtb rtf rtm rto rtr rtt taa tab taf tam tao tar tat tba tbb tbf tbm tbo tbr tbt tfa tfb tff tfm tfo tfr tft tma tmb tmf tmm tmo tmr tmt to- toa tob tof tom too tor tot tra trb trf trm tro trr trt tta ttb ttf ttm tto ttr ttt