-er a-a a-b a-i aaa aab aae aaf aai aan aao aar aas ab- aba abb abe abf abi abn abo abr abs aea aeb aee aef aei aen aeo aer aes af- afa afb afe aff afi afn afo afr afs ai- aia aib aie aif aii ain aio air ais an- ana anb ane anf ani ann ano anr ans aoa aob aoe aof aoi aon aoo aor aos ar- ara arb are arf ari arn aro arr ars as- asa asb ase asf asi asn aso asr ass baa bab bae baf bai ban bao bar bas bba bbb bbe bbf bbi bbn bbo bbr bbs be- bea beb bee bef bei ben beo ber bes bfa bfb bfe bff bfi bfn bfo bfr bfs bi- bia bib bie bif bii bin bio bir bis bna bnb bne bnf bni bnn bno bnr bns boa bob boe bof boi bon boo bor bos bra brb bre brf bri brn bro brr brs bsa bsb bse bsf bsi bsn bso bsr bss eaa eab eae eaf eai ean eao ear eas eba ebb ebe ebf ebi ebn ebo ebr ebs eea eeb eee eef een eeo eer ees ef- efa efb efe eff efi efo efr efs eia eib eie eif eii ein eio eir eis en- ena enb ene enf eni enn eno enr ens eo- eoa eob eoe eof eoi eon eoo eor eos era erb ere erf eri ern ero err ers es- esa esb ese esf esi esn eso esr ess faa fab fae faf fai fan fao far fas fba fbb fbe fbf fbi fbn fbo fbr fbs fea feb fee fef fei fen feo fer fes ffa ffe fff ffi ffn ffo ffr ffs fia fib fie fif fii fin fir fis fna fnb fne fnf fni fnn fnr fns foa fob foe fof foi fon foo for fos fra frb fre frf fri frn fro frr frs fsa fsb fse fsf fsi fsn fso fsr fss i-f ia- iaa iab iae iaf iai ian iao iar ias iba ibb ibe ibf ibi ibn ibo ibr ibs ie- iea iee ief iei ien ier ies ifa ifb ife iff ifi ifn ifo ifr ifs iia iib iie iif iii iin iio iir iis in- ina inb ine inf ini inn ino inr ins io- ioa iob ioe iof ioi ion ioo ior ios ir- ira irb ire irf iri irn iro irr irs is- isa isb ise isf isi isn iso isr iss n-i naa nab nae naf nai nan nao nar nas nba nbb nbe nbf nbi nbn nbo nbr nbs ne- nea neb nee nef nei nen neo ner nes nfa nfb nfe nff nfi nfn nfo nfr nfs nia nib nie nif nii nin nio nir nis nna nnb nne nnf nni nnn nno nns no- noa nob noe nof noi non noo nor nos nra nrb nre nrf nri nrn nro nrr nrs nsa nsb nse nsf nsi nsn nso nsr nss o-i oaa oab oae oaf oai oan oao oar oas ob- oba obb obe obf obi obn obo obr obs oea oeb oee oef oei oen oeo oer oes of- ofa ofb ofe off ofi ofn ofo ofr ofs oia oib oie oif oii oin oio oir ois on- ona onb one onf oni onn ono onr ons oo- ooa oob oof ooi oon ooo oor oos or- ora orb ore orf ori orn oro orr ors os- osa osb ose osf osi osn oso osr oss ra- raa rab rae raf rai ran rao rar ras rba rbb rbe rbf rbi rbn rbo rbr rbs re- rea reb ree ref rei ren reo rer res rfa rfb rfe rff rfi rfn rfo rfr rfs ria rib rie rif rii rin rio rir ris rna rnb rni rnn rno rnr rns roa rob roe rof roi ron roo ror ros rra rrb rrf rri rrn rrr rrs rsa rsb rse rsf rsi rsn rso rsr rss saa sab sae saf sai san sao sar sas sba sbb sbe sbf sbi sbn sbo sbr sbs se- sea seb see sef sei sen seo ser ses sfa sfb sfe sff sfi sfn sfo sfr sfs sia sib sie sif sii sin sio sir sis sna snb sne snf sni snn sno snr sns soa sob soe sof soi son soo sor sos sr- sra srb sre srf sri srn sro srr srs ss- ssa ssb sse ssf ssi ssn sso ssr sss