-er a-a a-b a-c a-t aaa aab aac aae aag aao aar aat ab- aba abb abc abe abg abo abr abt ac- aca acb acc ace acg aco acr act aea aeb aec aee aeg aeo aer aet ag- aga agb agc age agg ago agr agt aoa aob aoc aoe aog aoo aor aot ar- ara arb arc are arg aro arr art at- ata atb atc ate atg ato atr att baa bab bac bae bag bao bar bat bba bbb bbc bbe bbg bbo bbr bbt bca bcb bcc bce bcg bco bcr bct be- bea beb bec bee beg beo ber bet bga bgb bgc bge bgg bgo bgr bgt boa bob boc boe bog boo bor bot bra brb bre brg bro brr brt bta btb btc bte btg bto btr btt c-- caa cab cac cae cag cao car cat cba cbb cbc cbe cbg cbo cbr cbt cca ccb ccc cce ccg cco ccr cct ce- cea ceb cec cee ceg ceo cer cet cga cgb cgc cge cgg cgo cgr cgt co- coa cob coc coe cog coo cor cot cra crb crc cre crg cro crr crt cta ctb ctc cte ctg cto ctr ctt eaa eab eac eae eag eao ear eat eba ebb ebc ebe ebg ebo ebr ebt ec- eca ecb ecc ece ecg eco ecr ect eea eeb eec eee eeg eeo eer eet ega egb egc ege egg ego egr egt eo- eoa eob eoc eoe eog eoo eor eot era erb erc ere erg ero err ert eta etb etc ete etg eto etr ett gaa gab gac gae gag gao gar gat gba gbc gbe gbg gbo gbr gbt gca gcb gcc gce gcg gco gcr gct ge- gea geb gec gee geg geo ger get gga ggb ggc ggg ggo ggr ggt goa gob goc goe gog goo gor got gra grb grc gre grg gro grr grt gta gtb gtc gte gtg gto gtr gtt oaa oab oac oae oag oao oar oat ob- oba obb obc obe obg obo obr obt oc- oca ocb occ ocg oco ocr oct oea oeb oec oee oeg oeo oer oet oga ogc oge ogg ogo ogt oo- ooa oob ooc oog ooo oor oot or- ora orb orc ore org oro orr ort ot- ota otb otc ote otg oto otr ott ra- raa rab rac rae rag rao rar rat rba rbb rbc rbe rbg rbo rbr rbt rca rcb rcc rce rcg rco rcr rct re- rea reb rec ree reg reo rer ret rga rgb rgc rge rgg rgo rgr rgt roa rob roc roe rog roo ror rot rra rrb rrc rrg rrr rrt rta rtb rtc rte rtg rto rtr rtt taa tab tac tae tag tao tar tat tba tbb tbc tbe tbg tbo tbr tbt tca tcb tcc tce tcg tco tcr tct te- tea teb tec tee teg teo ter tet tga tgb tgc tge tgg tgo tgr tgt to- toa tob toc toe tog too tor tot tra trb trc tre trg tro trr trt tta ttb ttc tte ttg tto ttr ttt