a-a a-b a-t aaa aab aaf aag aao aar aat ab- aba abb abf abg abo abr abt af- afa afb aff afg afo afr aft ag- aga agb agf agg ago agr agt aoa aob aof aog aoo aor aot ar- ara arb arf arg aro arr art at- ata atb atf atg ato atr att baa bab baf bag bao bar bat bba bbb bbf bbg bbo bbr bbt bfa bfb bff bfg bfo bfr bft bga bgb bgf bgg bgo bgr bgt boa bob bof bog boo bor bot bra brb brf brg bro brr brt bta btb btf btg bto btr btt faa fab faf fag fao far fat fba fbb fbf fbg fbo fbr fbt ffa fff ffg ffo ffr fft fga fgb fgf fgg fgr fgt foa fob fof fog foo for fot fra frb frf frg fro frr frt fta ftb ftf ftg fto ftr ftt gaa gab gaf gag gao gar gat gba gbf gbg gbo gbr gbt gfa gfb gff gfo gfr gft gga ggb ggg ggo ggr ggt goa gob gof gog goo gor got gra grb grf grg gro grr grt gta gtb gtf gtg gto gtr gtt oaa oab oaf oag oao oar oat ob- oba obb obf obg obo obr obt of- ofa ofb off ofg ofo ofr oft oga ogf ogg ogo ogt oo- ooa oob oof oog ooo oor oot or- ora orb orf org oro orr ort ot- ota otb otf otg oto otr ott ra- raa rab raf rag rao rar rat rba rbb rbf rbg rbo rbr rbt rfa rfb rff rfg rfo rfr rft rga rgb rgf rgg rgo rgr rgt roa rob rof rog roo ror rot rra rrb rrf rrg rrr rrt rta rtb rtf rtg rto rtr rtt taa tab taf tag tao tar tat tba tbb tbf tbg tbo tbr tbt tfa tfb tff tfg tfo tfr tft tga tgb tgf tgg tgo tgr tgt to- toa tob tof tog too tor tot tra trb trf trg tro trr trt tta ttb ttf ttg tto ttr ttt