-er bbb bbe bbk bbo bbr be- beb bee bek beo ber bez bkb bke bkk bko bkr bob boe bok boo bor boz brb bre brk bro brr brz bze bzo bzr bzz ebb ebe ebk ebo ebr eeb eee eek eeo eer ekb eke eko ekr eo- eob eoe eok eoo eor erb ere erk ero err erz eze ezo ezr ezz k-z kbb kbe kbk kbo kbr kbz ke- keb kee kek keo ker kez kkb kke kkk kkr kob koe kok koo kor koz krk kro krr kzo ob- obb obe obk obo obr oeb oee oeo oer okb oke okk oko okr oo- oob ook ooo oor or- orb ore ork oro orr orz oze ozo ozz rbb rbe rbk rbo rbr re- reb ree rek reo rer rez rkb rke rkk rko rkz rob roe rok roo ror roz rrb rrk rrr rzb rze rzo zbb zbr zeb zee zek zeo zer zez zo- zob zoe zok zoo zor zro zzr zzz