-er b-u bbb bbe bbk bbr bbu be- beb bee bek ber beu bez bkb bke bkk bkr brb bre brk brr bru brz bub bue buk bur buu buz bze bzr bzu bzz ebb ebe ebk ebr ebu eeb eee eek eer ekb eke ekr eku erb ere erk err eru erz eu- eub eue eur eze ezr ezz k-z kbb kbe kbk kbr kbu kbz ke- keb kee kek ker kez kkb kke kkk kkr kku krk krr kru kub kue kuk kur kuu rbb rbe rbk rbr rbu re- reb ree rek rer reu rez rkb rke rkk rku rkz rrb rrk rrr rru rub rue ruk rur ruu ruz rzb rze ubb ube ubk ubr ubu ueb uee uer ukb uke ukk ukr uku ukz ur- urb ure urk urr uru urz uue uur uuu uzb uzu zbb zbr zeb zee zek zer zez zub zuk zur zuz zzr zzz