-er b-u bbb bbc bbe bbk bbl bbr bbu bcb bcc bce bck bcl bcr bcu be- beb bec bee bek bel ber beu bkb bkc bke bkk bkl bkr blb blc ble blk bll blr blu brb bre brk brl brr bru bub buc bue buk bul bur buu c-- cbb cbc cbe cbk cbl cbr cbu ccb ccc cce cck ccl ccr ccu ce- ceb cec cee cek cel cer ceu ckb ckc cl- clb clc cle clk cll clr clu crb crc cre crk crl crr cru cub cuc cue cuk cul cur cuu ebb ebc ebe ebk ebl ebr ebu ec- ecb ecc ece eck ecl ecr ecu eeb eec eee eek eel eer ekb ekc eke ekl ekr eku elb elc ele elk ell elr elu erb erc ere erk erl err eru eu- eub euc eue eul eur kbb kbc kbe kbk kbl kbr kbu kcb kcc kce kck kcl kcr kcu ke- keb kec kee kek kel ker kkb kkc kke kkk kkl kkr kku kl- klb klc klr klu krc krk krl krr kru kub kuc kue kuk kul kur kuu lbb lbc lbe lbk lbl lbr lbu lcb lcc lce lck lcl lcr lcu leb lec lee lek lel ler leu lkb lkl lkr llb llc lle llk lll llr llu lrb lrc lrk lrr lru lub luc lue luk lul lur luu rbb rbc rbe rbk rbl rbr rbu rcb rcc rce rcl rcr rcu re- reb rec ree rek rel rer reu rkb rkc rke rkk rku rlc rle rll rlr rlu rrb rrc rrk rrl rrr rru rub ruc rue ruk rur ruu ubb ubc ube ubk ubl ubr ubu ucb ucc uce uck ucl ucr ucu ueb uec uee uel uer ukb ukc uke ukk ukl ukr uku ulb ulc ule ulk ull ulr ulu ur- urb urc ure urk url urr uru uuc uue uur uuu