-er a-a a-b a-c aaa aab aac aae aag aak aar ab- aba abb abc abe abg abk abr ac- aca acb acc ace acg ack acr aea aeb aec aee aeg aek aer ag- aga agb agc age agg agk agr aka akb akc ake akg akk akr ar- ara arb arc are arg ark arr baa bab bac bae bag bak bar bba bbb bbc bbe bbg bbk bbr bca bcb bcc bce bcg bck bcr be- bea beb bec bee beg bek ber bga bgb bgc bge bgg bgk bgr bka bkb bkc bke bkg bkk bkr bra brb bre brg brk brr c-- caa cab cac cae cag cak car cba cbb cbc cbe cbg cbk cbr cca ccb ccc cce ccg cck ccr ce- cea ceb cec cee ceg cek cer cga cgb cgc cge cgg cgr cka ckb ckc cra crb crc cre crg crk crr eaa eab eac eae eag eak ear eba ebb ebc ebe ebg ebk ebr ec- eca ecb ecc ece ecg eck ecr eea eeb eec eee eeg eek eer ega egb egc ege egg egr eka ekb ekc eke ekg ekr era erb erc ere erg erk err gaa gab gac gae gag gak gar gba gbc gbe gbg gbk gbr gca gcb gcc gce gcg gck gcr ge- gea geb gec gee geg gek ger gga ggb ggc ggg ggr gka gkb gra grb grc gre grg grk grr ka- kaa kab kac kae kag kak kar kba kbb kbc kbe kbk kbr kca kcb kcc kce kcg kck kcr ke- kea keb kec kee keg kek ker kga kgb kgc kkb kkc kke kkk kkr kra krc krg krk krr ra- raa rab rac rae rag rak rar rba rbb rbc rbe rbg rbk rbr rca rcb rcc rce rcg rcr re- rea reb rec ree reg rek rer rga rgb rgc rge rgg rgk rgr rkb rkc rke rkg rkk rra rrb rrc rrg rrk rrr