-er a-a a-b aaa aab aae aan aar aas ab- aba abb abe abn abr abs aea aeb aee aen aer aes an- ana anb ane ann anr ans ar- ara arb are arn arr ars as- asa asb ase asn asr ass baa bab bae ban bar bas bba bbb bbe bbn bbr bbs be- bea beb bee ben ber bes bna bnb bne bnn bnr bns bra brb bre brn brr brs bsa bsb bse bsn bsr bss eaa eab eae ean ear eas eba ebb ebe ebn ebr ebs eea eeb eee een eer ees en- ena enb ene enn enr ens era erb ere ern err ers es- esa esb ese esn esr ess naa nab nae nan nar nas nba nbb nbe nbn nbr nbs ne- nea neb nee nen ner nes nna nnb nne nnn nns nra nrb nre nrn nrr nrs nsa nsb nse nsn nsr nss ra- raa rab rae ran rar ras rba rbb rbe rbn rbr rbs re- rea reb ree ren rer res rna rnb rnn rnr rns rra rrb rrn rrr rrs rsa rsb rse rsn rsr rss saa sab sae san sar sas sba sbb sbe sbn sbr sbs se- sea seb see sen ser ses sna snb sne snn snr sns sr- sra srb sre srn srr srs ss- ssa ssb sse ssn ssr sss