-er bbb bbe bbk bbn bbo bbr be- beb bee bek ben beo ber bez bkb bke bkk bkn bko bkr bnb bne bnk bnn bno bnr bnz bob boe bok bon boo bor boz brb bre brk brn bro brr brz bze bzn bzo bzr bzz ebb ebe ebk ebn ebo ebr eeb eee eek een eeo eer ekb eke eko ekr en- enb ene enk enn eno enr enz eo- eob eoe eok eon eoo eor erb ere erk ern ero err erz eze ezo ezr ezz k-z kbb kbe kbk kbn kbo kbr kbz ke- keb kee kek ken keo ker kez kkb kke kkk kkn kkr kn- kne knk knn kno knr kob koe kok kon koo kor koz krk krn kro krr kzo nbb nbe nbk nbn nbo nbr ne- neb nee nek nen neo ner nez nke nkk nkn nko nkr nnb nne nnk nnn nno nnz no- nob noe nok non noo nor noz nrb nre nrk nrn nro nrr nrz nzb nze nzo nzz ob- obb obe obk obn obo obr oeb oee oen oeo oer okb oke okk oko okr on- onb one onk onn ono onr oo- oob ook oon ooo oor or- orb ore ork orn oro orr orz oze ozo ozz rbb rbe rbk rbn rbo rbr re- reb ree rek ren reo rer rez rkb rke rkk rko rkz rnb rnn rno rnr rnz rob roe rok ron roo ror roz rrb rrk rrn rrr rzb rze rzo zbb zbr zeb zee zek zen zeo zer zez zne znn zno zo- zob zoe zok zon zoo zor zro zzr zzz