-er bbb bbe bbi bbk bbr bbs be- beb bee bei bek ber bes bi- bib bie bii bik bir bis bkb bke bkk bkr bks brb bre bri brk brr brs bsb bse bsi bsk bsr bss ebb ebe ebi ebk ebr ebs eeb eee eek eer ees eib eie eii eik eir eis ekb eke eki ekr eks erb ere eri erk err ers es- esb ese esi esk esr ess ibb ibe ibi ibk ibr ibs ie- iee iei iek ier ies iib iie iii iir iis ikb ike iki ikk ikr iks ir- irb ire iri irk irr irs is- isb ise isi isk isr iss kbb kbe kbi kbk kbr kbs ke- keb kee kei kek ker kes kib kie kii kik kir kis kkb kke kki kkk kkr kks kri krk krr krs ksb kse ksi ksk ksr kss rbb rbe rbi rbk rbr rbs re- reb ree rei rek rer res rib rie rii rik rir ris rkb rke rkk rks rrb rri rrk rrr rrs rsb rse rsi rsk rsr rss sbb sbe sbi sbk sbr sbs se- seb see sei sek ser ses sib sie sii sik sir sis sk- skb ske ski skk skr sks sr- srb sre sri srk srr srs ss- ssb sse ssi ssk ssr sss