-er a-a a-b a-c aaa aab aac aae aag aak aar aau ab- aba abb abc abe abg abk abr abu ac- aca acb acc ace acg ack acr acu aea aeb aec aee aeg aek aer aeu ag- aga agb agc age agg agk agr agu aka akb akc ake akg akk akr aku ar- ara arb arc are arg ark arr aru au- aua aub auc aue aug auk aur b-u baa bab bac bae bag bak bar bau bba bbb bbc bbe bbg bbk bbr bbu bca bcb bcc bce bcg bck bcr bcu be- bea beb bec bee beg bek ber beu bga bgb bgc bge bgg bgk bgr bgu bka bkb bkc bke bkg bkk bkr bra brb bre brg brk brr bru bua bub buc bue bug buk bur buu c-- caa cab cac cae cag cak car cau cba cbb cbc cbe cbg cbk cbr cbu cca ccb ccc cce ccg cck ccr ccu ce- cea ceb cec cee ceg cek cer ceu cga cgb cgc cge cgg cgr cgu cka ckb ckc cra crb crc cre crg crk crr cru cua cub cuc cue cug cuk cur cuu eaa eab eac eae eag eak ear eau eba ebb ebc ebe ebg ebk ebr ebu ec- eca ecb ecc ece ecg eck ecr ecu eea eeb eec eee eeg eek eer ega egb egc ege egg egr egu eka ekb ekc eke ekg ekr eku era erb erc ere erg erk err eru eu- eua eub euc eue eug eur gaa gab gac gae gag gak gar gau gba gbc gbe gbg gbk gbr gbu gca gcb gcc gce gcg gck gcr gcu ge- gea geb gec gee geg gek ger geu gga ggb ggc ggg ggr ggu gka gkb gra grb grc gre grg grk grr gru gu- gua gub guc gue gug guk gur guu ka- kaa kab kac kae kag kak kar kau kba kbb kbc kbe kbk kbr kbu kca kcb kcc kce kcg kck kcr kcu ke- kea keb kec kee keg kek ker kga kgb kgc kgu kkb kkc kke kkk kkr kku kra krc krg krk krr kru kub kuc kue kug kuk kur kuu ra- raa rab rac rae rag rak rar rau rba rbb rbc rbe rbg rbk rbr rbu rca rcb rcc rce rcg rcr rcu re- rea reb rec ree reg rek rer reu rga rgb rgc rge rgg rgk rgr rkb rkc rke rkg rkk rku rra rrb rrc rrg rrk rrr rru rua rub ruc rue rug ruk rur ruu ua- uaa uab uac uae uag uak uar uau uba ubb ubc ube ubg ubk ubr ubu uca ucb ucc uce ucg uck ucr ucu uea ueb uec uee ueg uer uga ugb ugc uge ugg ugk ugr ugu uka ukb ukc uke ukk ukr uku ur- ura urb urc ure urg urk urr uru uua uuc uue uug uur uuu