-er a-a a-b a-i aaa aab aae aai aan aao aar aas ab- aba abb abe abi abn abo abr abs aea aeb aee aei aen aeo aer aes ai- aia aib aie aii ain aio air ais an- ana anb ane ani ann ano anr ans aoa aob aoe aoi aon aoo aor aos ar- ara arb are ari arn aro arr ars as- asa asb ase asi asn aso asr ass baa bab bae bai ban bao bar bas bba bbb bbe bbi bbn bbo bbr bbs be- bea beb bee bei ben beo ber bes bi- bia bib bie bii bin bio bir bis bna bnb bne bni bnn bno bnr bns boa bob boe boi bon boo bor bos bra brb bre bri brn bro brr brs bsa bsb bse bsi bsn bso bsr bss eaa eab eae eai ean eao ear eas eba ebb ebe ebi ebn ebo ebr ebs eea eeb eee een eeo eer ees eia eib eie eii ein eio eir eis en- ena enb ene eni enn eno enr ens eo- eoa eob eoe eoi eon eoo eor eos era erb ere eri ern ero err ers es- esa esb ese esi esn eso esr ess ia- iaa iab iae iai ian iao iar ias iba ibb ibe ibi ibn ibo ibr ibs ie- iea iee iei ien ier ies iia iib iie iii iin iio iir iis in- ina inb ine ini inn ino inr ins io- ioa iob ioe ioi ion ioo ior ios ir- ira irb ire iri irn iro irr irs is- isa isb ise isi isn iso isr iss n-i naa nab nae nai nan nao nar nas nba nbb nbe nbi nbn nbo nbr nbs ne- nea neb nee nei nen neo ner nes nia nib nie nii nin nio nir nis nna nnb nne nni nnn nno nns no- noa nob noe noi non noo nor nos nra nrb nre nri nrn nro nrr nrs nsa nsb nse nsi nsn nso nsr nss o-i oaa oab oae oai oan oao oar oas ob- oba obb obe obi obn obo obr obs oea oeb oee oei oen oeo oer oes oia oib oie oii oin oio oir ois on- ona onb one oni onn ono onr ons oo- ooa oob ooi oon ooo oor oos or- ora orb ore ori orn oro orr ors os- osa osb ose osi osn oso osr oss ra- raa rab rae rai ran rao rar ras rba rbb rbe rbi rbn rbo rbr rbs re- rea reb ree rei ren reo rer res ria rib rie rii rin rio rir ris rna rnb rni rnn rno rnr rns roa rob roe roi ron roo ror ros rra rrb rri rrn rrr rrs rsa rsb rse rsi rsn rso rsr rss saa sab sae sai san sao sar sas sba sbb sbe sbi sbn sbo sbr sbs se- sea seb see sei sen seo ser ses sia sib sie sii sin sio sir sis sna snb sne sni snn sno snr sns soa sob soe soi son soo sor sos sr- sra srb sre sri srn sro srr srs ss- ssa ssb sse ssi ssn sso ssr sss