-er b-u bbb bbc bbe bbg bbk bbr bbu bcb bcc bce bcg bck bcr bcu be- beb bec bee beg bek ber beu bgb bgc bge bgg bgk bgr bgu bkb bkc bke bkg bkk bkr brb bre brg brk brr bru bub buc bue bug buk bur buu c-- cbb cbc cbe cbg cbk cbr cbu ccb ccc cce ccg cck ccr ccu ce- ceb cec cee ceg cek cer ceu cgb cgc cge cgg cgr cgu ckb ckc crb crc cre crg crk crr cru cub cuc cue cug cuk cur cuu ebb ebc ebe ebg ebk ebr ebu ec- ecb ecc ece ecg eck ecr ecu eeb eec eee eeg eek eer egb egc ege egg egr egu ekb ekc eke ekg ekr eku erb erc ere erg erk err eru eu- eub euc eue eug eur gbc gbe gbg gbk gbr gbu gcb gcc gce gcg gck gcr gcu ge- geb gec gee geg gek ger geu ggb ggc ggg ggr ggu gkb grb grc gre grg grk grr gru gu- gub guc gue gug guk gur guu kbb kbc kbe kbk kbr kbu kcb kcc kce kcg kck kcr kcu ke- keb kec kee keg kek ker kgb kgc kgu kkb kkc kke kkk kkr kku krc krg krk krr kru kub kuc kue kug kuk kur kuu rbb rbc rbe rbg rbk rbr rbu rcb rcc rce rcg rcr rcu re- reb rec ree reg rek rer reu rgb rgc rge rgg rgk rgr rkb rkc rke rkg rkk rku rrb rrc rrg rrk rrr rru rub ruc rue rug ruk rur ruu ubb ubc ube ubg ubk ubr ubu ucb ucc uce ucg uck ucr ucu ueb uec uee ueg uer ugb ugc uge ugg ugk ugr ugu ukb ukc uke ukk ukr uku ur- urb urc ure urg urk urr uru uuc uue uug uur uuu