-er b-u bbb bbe bbk bbr bbu be- beb bee bek ber beu bev bkb bke bkk bkr bkv brb bre brk brr bru brv bub bue buk bur buu bvb bve bvk bvr bvu bvv ebb ebe ebk ebr ebu ebv eeb eee eek eer eev ekb eke ekr eku ekv erb ere erk err eru erv eu- eub eue eur euv evb eve evr evv kbb kbe kbk kbr kbu ke- keb kee kek ker kev kkb kke kkk kkr kku kkv krk krr kru krv kub kue kuk kur kuu kvb kvk kvr kvv rbb rbe rbk rbr rbu re- reb ree rek rer reu rev rkb rke rkk rku rkv rrb rrk rrr rru rub rue ruk rur ruu ruv rvb rve rvr rvu rvv ubb ube ubk ubr ubu ubv ueb uee uer ukb uke ukk ukr uku ur- urb ure urk urr uru uue uur uuu uvb uve uvu uvv v-e vbk vbr vbv veb vee vek ver veu vkb vrb vre vrk vrr vru vue vuk vur vuv vvb vvr vvv