-er b-u bbb bbd bbe bbn bbr bbu bdb bdd bde bdr bdu be- beb bed bee ben ber beu bnb bnd bne bnn bnr bnu brb brd bre brn brr bru bub bud bue bun bur buu dbb dbd dbe dbn dbr dbu ddb ddd dde ddn ddr ddu de- deb ded dee den der deu dnb dnd dne dnn dnr drb drd dre drn drr dru dub dud due dun dur ebb ebd ebe ebn ebr ebu ed- edb edd ede edn edr edu eeb eed eee een eer en- enb end ene enn enr enu erb erd ere ern err eru eu- eub eud eue eun eur nbb nbd nbe nbn nbr nbu ndb ndd nde ndn ndr ndu ne- neb ned nee nen ner neu nnb nne nnn nnu nrb nrd nre nrn nrr nru nub nud nue nun nur nuu rbb rbd rbe rbn rbr rbu rdb rdd rde rdn rdr rdu re- reb red ree ren rer reu rnb rnd rnn rnr rnu rrb rrd rrn rrr rru rub rud rue run rur ruu ubb ube ubn ubr ubu udb udd ude udn udr udu ueb ued uee uen uer un- unb und une unn unr unu ur- urb urd ure urn urr uru uue uun uur uuu