-er a-a a-b aaa aab aae aan aao aar aas ab- aba abb abe abn abo abr abs aea aeb aee aen aeo aer aes an- ana anb ane ann ano anr ans aoa aob aoe aon aoo aor aos ar- ara arb are arn aro arr ars as- asa asb ase asn aso asr ass baa bab bae ban bao bar bas bba bbb bbe bbn bbo bbr bbs be- bea beb bee ben beo ber bes bna bnb bne bnn bno bnr bns boa bob boe bon boo bor bos bra brb bre brn bro brr brs bsa bsb bse bsn bso bsr bss eaa eab eae ean eao ear eas eba ebb ebe ebn ebo ebr ebs eea eeb eee een eeo eer ees en- ena enb ene enn eno enr ens eo- eoa eob eoe eon eoo eor eos era erb ere ern ero err ers es- esa esb ese esn eso esr ess naa nab nae nan nao nar nas nba nbb nbe nbn nbo nbr nbs ne- nea neb nee nen neo ner nes nna nnb nne nnn nno nns no- noa nob noe non noo nor nos nra nrb nre nrn nro nrr nrs nsa nsb nse nsn nso nsr nss oaa oab oae oan oao oar oas ob- oba obb obe obn obo obr obs oea oeb oee oen oeo oer oes on- ona onb one onn ono onr ons oo- ooa oob oon ooo oor oos or- ora orb ore orn oro orr ors os- osa osb ose osn oso osr oss ra- raa rab rae ran rao rar ras rba rbb rbe rbn rbo rbr rbs re- rea reb ree ren reo rer res rna rnb rnn rno rnr rns roa rob roe ron roo ror ros rra rrb rrn rrr rrs rsa rsb rse rsn rso rsr rss saa sab sae san sao sar sas sba sbb sbe sbn sbo sbr sbs se- sea seb see sen seo ser ses sna snb sne snn sno snr sns soa sob soe son soo sor sos sr- sra srb sre srn sro srr srs ss- ssa ssb sse ssn sso ssr sss