a-a a-b a-t aaa aab aag aao aar aat aax ab- aba abb abg abo abr abt abx ag- aga agb agg ago agr agt agx aoa aob aog aoo aor aot aox ar- ara arb arg aro arr art arx at- ata atb atg ato atr att atx ax- axa axo axr axt axx baa bab bag bao bar bat bax bba bbb bbg bbo bbr bbt bbx bga bgb bgg bgo bgr bgt bgx boa bob bog boo bor bot box bra brb brg bro brr brt brx bta btb btg bto btr btt btx bxb bxo bxx gaa gab gag gao gar gat gba gbg gbo gbr gbt gbx gga ggb ggg ggo ggr ggt goa gob gog goo gor got gox gra grb grg gro grr grt grx gta gtb gtg gto gtr gtt gtx gxa gxt oaa oab oag oao oar oat oax ob- oba obb obg obo obr obt obx oga ogg ogo ogt ogx oo- ooa oob oog ooo oor oot oox or- ora orb org oro orr ort orx ot- ota otb otg oto otr ott ox- oxa oxb oxo oxt oxx ra- raa rab rag rao rar rat rax rba rbb rbg rbo rbr rbt rbx rga rgb rgg rgo rgr rgt rgx roa rob rog roo ror rot rox rra rrb rrg rrr rrt rta rtb rtg rto rtr rtt rtx rxr t-x taa tab tag tao tar tat tax tba tbb tbg tbo tbr tbt tga tgb tgg tgo tgr tgt to- toa tob tog too tor tot tox tra trb trg tro trr trt trx tta ttb ttg tto ttr ttt ttx txt xaa xag xar xat xbr xbx xoa xog xoo xor xot xox xrt xrx xtr xtx xxo xxx