-er a-a a-b a-c a-t aaa aab aac aae aag aak aar aat ab- aba abb abc abe abg abk abr abt ac- aca acb acc ace acg ack acr act aea aeb aec aee aeg aek aer aet ag- aga agb agc age agg agk agr agt aka akb akc ake akg akk akr ar- ara arb arc are arg ark arr art at- ata atb atc ate atg atr att baa bab bac bae bag bak bar bat bba bbb bbc bbe bbg bbk bbr bbt bca bcb bcc bce bcg bck bcr bct be- bea beb bec bee beg bek ber bet bga bgb bgc bge bgg bgk bgr bgt bka bkb bkc bke bkg bkk bkr bkt bra brb bre brg brk brr brt bta btb btc bte btg btk btr btt c-- caa cab cac cae cag cak car cat cba cbb cbc cbe cbg cbk cbr cbt cca ccb ccc cce ccg cck ccr cct ce- cea ceb cec cee ceg cek cer cet cga cgb cgc cge cgg cgr cgt cka ckb ckc ckt cra crb crc cre crg crk crr crt cta ctb ctc cte ctg ctk ctr ctt eaa eab eac eae eag eak ear eat eba ebb ebc ebe ebg ebk ebr ebt ec- eca ecb ecc ece ecg eck ecr ect eea eeb eec eee eeg eek eer eet ega egb egc ege egg egr egt eka ekb ekc eke ekg ekr ekt era erb erc ere erg erk err ert eta etb etc ete etg etk etr ett gaa gab gac gae gag gak gar gat gba gbc gbe gbg gbk gbr gbt gca gcb gcc gce gcg gck gcr gct ge- gea geb gec gee geg gek ger get gga ggb ggc ggg ggr ggt gka gkb gkt gra grb grc gre grg grk grr grt gta gtb gtc gte gtg gtk gtr gtt k-t ka- kaa kab kac kae kag kak kar kat kba kbb kbc kbe kbk kbr kca kcb kcc kce kcg kck kcr kct ke- kea keb kec kee keg kek ker ket kga kgb kgc kkb kkc kke kkk kkr kkt kra krc krg krk krr krt kta ktb ktc kte ktg ktk ktr ktt ra- raa rab rac rae rag rak rar rat rba rbb rbc rbe rbg rbk rbr rbt rca rcb rcc rce rcg rcr rct re- rea reb rec ree reg rek rer ret rga rgb rgc rge rgg rgk rgr rgt rkb rkc rke rkg rkk rkt rra rrb rrc rrg rrk rrr rrt rta rtb rtc rte rtg rtk rtr rtt taa tab tac tae tag tak tar tat tba tbb tbc tbe tbg tbk tbr tbt tca tcb tcc tce tcg tck tcr tct te- tea teb tec tee teg tek ter tet tga tgb tgc tge tgg tgk tgr tgt tka tkb tkc tke tkg tkk tkr tkt tra trb trc tre trg trk trr trt tta ttb ttc tte ttg ttk ttr ttt