-er a-a a-b a-t aaa aab aae aag aao aar aat ab- aba abb abe abg abo abr abt aea aeb aee aeg aeo aer aet ag- aga agb age agg ago agr agt aoa aob aoe aog aoo aor aot ar- ara arb are arg aro arr art at- ata atb ate atg ato atr att baa bab bae bag bao bar bat bba bbb bbe bbg bbo bbr bbt be- bea beb bee beg beo ber bet bga bgb bge bgg bgo bgr bgt boa bob boe bog boo bor bot bra brb bre brg bro brr brt bta btb bte btg bto btr btt eaa eab eae eag eao ear eat eba ebb ebe ebg ebo ebr ebt eea eeb eee eeg eeo eer eet ega egb ege egg ego egr egt eo- eoa eob eoe eog eoo eor eot era erb ere erg ero err ert eta etb ete etg eto etr ett gaa gab gae gag gao gar gat gba gbe gbg gbo gbr gbt ge- gea geb gee geg geo ger get gga ggb ggg ggo ggr ggt goa gob goe gog goo gor got gra grb gre grg gro grr grt gta gtb gte gtg gto gtr gtt oaa oab oae oag oao oar oat ob- oba obb obe obg obo obr obt oea oeb oee oeg oeo oer oet oga oge ogg ogo ogt oo- ooa oob oog ooo oor oot or- ora orb ore org oro orr ort ot- ota otb ote otg oto otr ott ra- raa rab rae rag rao rar rat rba rbb rbe rbg rbo rbr rbt re- rea reb ree reg reo rer ret rga rgb rge rgg rgo rgr rgt roa rob roe rog roo ror rot rra rrb rrg rrr rrt rta rtb rte rtg rto rtr rtt taa tab tae tag tao tar tat tba tbb tbe tbg tbo tbr tbt te- tea teb tee teg teo ter tet tga tgb tge tgg tgo tgr tgt to- toa tob toe tog too tor tot tra trb tre trg tro trr trt tta ttb tte ttg tto ttr ttt