-er bbb bbe bbi bbk bbn bbo bbr bbs be- beb bee bei bek ben beo ber bes bi- bib bie bii bik bin bio bir bis bkb bke bkk bkn bko bkr bks bnb bne bni bnk bnn bno bnr bns bob boe boi bok bon boo bor bos brb bre bri brk brn bro brr brs bsb bse bsi bsk bsn bso bsr bss ebb ebe ebi ebk ebn ebo ebr ebs eeb eee eek een eeo eer ees eib eie eii eik ein eio eir eis ekb eke eki eko ekr eks en- enb ene eni enk enn eno enr ens eo- eob eoe eoi eok eon eoo eor eos erb ere eri erk ern ero err ers es- esb ese esi esk esn eso esr ess ibb ibe ibi ibk ibn ibo ibr ibs ie- iee iei iek ien ier ies iib iie iii iin iio iir iis ikb ike iki ikk iko ikr iks in- inb ine ini ink inn ino inr ins io- iob ioe ioi ion ioo ior ios ir- irb ire iri irk irn iro irr irs is- isb ise isi isk isn iso isr iss kbb kbe kbi kbk kbn kbo kbr kbs ke- keb kee kei kek ken keo ker kes kib kie kii kik kin kio kir kis kkb kke kki kkk kkn kkr kks kn- kne kni knk knn kno knr kob koe koi kok kon koo kor kos kri krk krn kro krr krs ksb kse ksi ksk ksn kso ksr kss n-i nbb nbe nbi nbk nbn nbo nbr nbs ne- neb nee nei nek nen neo ner nes nib nie nii nik nin nio nir nis nke nki nkk nkn nko nkr nks nnb nne nni nnk nnn nno nns no- nob noe noi nok non noo nor nos nrb nre nri nrk nrn nro nrr nrs nsb nse nsi nsk nsn nso nsr nss o-i ob- obb obe obi obk obn obo obr obs oeb oee oei oen oeo oer oes oib oie oii oik oin oio oir ois okb oke oki okk oko okr oks on- onb one oni onk onn ono onr ons oo- oob ooi ook oon ooo oor oos or- orb ore ori ork orn oro orr ors os- osb ose osi osk osn oso osr oss rbb rbe rbi rbk rbn rbo rbr rbs re- reb ree rei rek ren reo rer res rib rie rii rik rin rio rir ris rkb rke rkk rko rks rnb rni rnn rno rnr rns rob roe roi rok ron roo ror ros rrb rri rrk rrn rrr rrs rsb rse rsi rsk rsn rso rsr rss sbb sbe sbi sbk sbn sbo sbr sbs se- seb see sei sek sen seo ser ses sib sie sii sik sin sio sir sis sk- skb ske ski skk sko skr sks snb sne sni snk snn sno snr sns sob soe soi sok son soo sor sos sr- srb sre sri srk srn sro srr srs ss- ssb sse ssi ssk ssn sso ssr sss