-er -ol b-u bbb bbc bbe bbk bbl bbo bbr bbu bcb bcc bce bck bcl bco bcr bcu be- beb bec bee bek bel beo ber beu bkb bkc bke bkk bkl bko bkr blb blc ble blk bll blo blr blu bob boc boe bok bol boo bor bou brb bre brk brl bro brr bru bub buc bue buk bul buo bur buu c-- cbb cbc cbe cbk cbl cbo cbr cbu ccb ccc cce cck ccl cco ccr ccu ce- ceb cec cee cek cel ceo cer ceu ckb ckc cko cl- clb clc cle clk cll clo clr clu co- cob coc coe cok col coo cor cou crb crc cre crk crl cro crr cru cub cuc cue cuk cul cuo cur cuu ebb ebc ebe ebk ebl ebo ebr ebu ec- ecb ecc ece eck ecl eco ecr ecu eeb eec eee eek eel eeo eer ekb ekc eke ekl eko ekr eku elb elc ele elk ell elo elr elu eo- eob eoc eoe eok eol eoo eor eou erb erc ere erk erl ero err eru eu- eub euc eue eul eur kbb kbc kbe kbk kbl kbo kbr kbu kcb kcc kce kck kcl kcr kcu ke- keb kec kee kek kel keo ker kkb kkc kke kkk kkl kkr kku kl- klb klc klo klr klu kob koc koe kok kol koo kor kou krc krk krl kro krr kru kub kuc kue kuk kul kur kuu lbb lbc lbe lbk lbl lbo lbr lbu lcb lcc lce lck lcl lco lcr lcu leb lec lee lek lel leo ler leu lkb lkl lkr llb llc lle llk lll llo llr llu lob loc loe lok lol loo lor lou lrb lrc lrk lro lrr lru lub luc lue luk lul luo lur luu ob- obb obc obe obk obl obo obr obu oc- ocb occ ock ocl oco ocr ocu oeb oec oee oel oeo oer okb okc oke okk okl oko okr oku olb olc ole olk oll olo olu oo- oob ooc ook ool ooo oor or- orb orc ore ork orl oro orr oru ou- ouc oue ouk oul ouo our rbb rbc rbe rbk rbl rbo rbr rbu rcb rcc rce rcl rco rcr rcu re- reb rec ree rek rel reo rer reu rkb rkc rke rkk rko rku rlc rle rll rlo rlr rlu rob roc roe rok rol roo ror rou rrb rrc rrk rrl rrr rru rub ruc rue ruk ruo rur ruu ubb ubc ube ubk ubl ubo ubr ubu ucb ucc uce uck ucl uco ucr ucu ueb uec uee uel uer ukb ukc uke ukk ukl ukr uku ulb ulc ule ulk ull ulo ulr ulu uob uoc uoe uok uol uoo uor ur- urb urc ure urk url uro urr uru uuc uue uur uuu