-er bbb bbe bbk bbn bbr be- beb bee bek ben ber bkb bke bkk bkn bkr bnb bne bnk bnn bnr brb bre brk brn brr ebb ebe ebk ebn ebr eeb eee eek een eer ekb eke ekr en- enb ene enk enn enr erb ere erk ern err kbb kbe kbk kbn kbr ke- keb kee kek ken ker kkb kke kkk kkn kkr kn- kne knk knn knr krk krn krr nbb nbe nbk nbn nbr ne- neb nee nek nen ner nke nkk nkn nkr nnb nne nnk nnn nrb nre nrk nrn nrr rbb rbe rbk rbn rbr re- reb ree rek ren rer rkb rke rkk rnb rnn rnr rrb rrk rrn rrr