a-a a-b a-t aaa aab aag aao aar aat ab- aba abb abg abo abr abt ag- aga agb agg ago agr agt aoa aob aog aoo aor aot ar- ara arb arg aro arr art at- ata atb atg ato atr att baa bab bag bao bar bat bba bbb bbg bbo bbr bbt bga bgb bgg bgo bgr bgt boa bob bog boo bor bot bra brb brg bro brr brt bta btb btg bto btr btt gaa gab gag gao gar gat gba gbg gbo gbr gbt gga ggb ggg ggo ggr ggt goa gob gog goo gor got gra grb grg gro grr grt gta gtb gtg gto gtr gtt oaa oab oag oao oar oat ob- oba obb obg obo obr obt oga ogg ogo ogt oo- ooa oob oog ooo oor oot or- ora orb org oro orr ort ot- ota otb otg oto otr ott ra- raa rab rag rao rar rat rba rbb rbg rbo rbr rbt rga rgb rgg rgo rgr rgt roa rob rog roo ror rot rra rrb rrg rrr rrt rta rtb rtg rto rtr rtt taa tab tag tao tar tat tba tbb tbg tbo tbr tbt tga tgb tgg tgo tgr tgt to- toa tob tog too tor tot tra trb trg tro trr trt tta ttb ttg tto ttr ttt