a-a a-b a-i aaa aab aaf aai aak aan aao aar aas ab- aba abb abf abi abk abn abo abr abs af- afa afb aff afi afk afn afo afr afs ai- aia aib aif aii aik ain aio air ais aka akb aki akk akn ako akr aks an- ana anb anf ani ank ann ano anr ans aoa aob aof aoi aok aon aoo aor aos ar- ara arb arf ari ark arn aro arr ars as- asa asb asf asi ask asn aso asr ass baa bab baf bai bak ban bao bar bas bba bbb bbf bbi bbk bbn bbo bbr bbs bfa bfb bff bfi bfn bfo bfr bfs bi- bia bib bif bii bik bin bio bir bis bka bkb bkf bkk bkn bko bkr bks bna bnb bnf bni bnk bnn bno bnr bns boa bob bof boi bok bon boo bor bos bra brb brf bri brk brn bro brr brs bsa bsb bsf bsi bsk bsn bso bsr bss faa fab faf fai fak fan fao far fas fba fbb fbf fbi fbk fbn fbo fbr fbs ffa fff ffi ffk ffn ffo ffr ffs fia fib fif fii fik fin fir fis fka fkb fkf fki fkk fna fnb fnf fni fnk fnn fnr fns foa fob fof foi fok fon foo for fos fra frb frf fri frk frn fro frr frs fsa fsb fsf fsi fsk fsn fso fsr fss i-f ia- iaa iab iaf iai ian iao iar ias iba ibb ibf ibi ibk ibn ibo ibr ibs ifa ifb iff ifi ifn ifo ifr ifs iia iib iif iii iin iio iir iis ika ikb ikf iki ikk iko ikr iks in- ina inb inf ini ink inn ino inr ins io- ioa iob iof ioi ion ioo ior ios ir- ira irb irf iri irk irn iro irr irs is- isa isb isf isi isk isn iso isr iss ka- kaa kab kaf kai kak kan kao kar kas kba kbb kbf kbi kbk kbn kbo kbr kbs kfa kff kfi kfo kfs kia kib kif kii kik kin kio kir kis kkb kki kkk kkn kkr kks kn- kna knf kni knk knn kno knr koa kob kof koi kok kon koo kor kos kra krf kri krk krn kro krr krs ksa ksb ksf ksi ksk ksn kso ksr kss n-i naa nab naf nai nak nan nao nar nas nba nbb nbf nbi nbk nbn nbo nbr nbs nfa nfb nff nfi nfk nfn nfo nfr nfs nia nib nif nii nik nin nio nir nis nka nkf nki nkk nkn nko nkr nks nna nnb nnf nni nnk nnn nno nns no- noa nob nof noi nok non noo nor nos nra nrb nrf nri nrk nrn nro nrr nrs nsa nsb nsf nsi nsk nsn nso nsr nss o-i oaa oab oaf oai oak oan oao oar oas ob- oba obb obf obi obk obn obo obr obs of- ofa ofb off ofi ofn ofo ofr ofs oia oib oif oii oik oin oio oir ois oka okb oki okk oko okr oks on- ona onb onf oni onk onn ono onr ons oo- ooa oob oof ooi ook oon ooo oor oos or- ora orb orf ori ork orn oro orr ors os- osa osb osf osi osk osn oso osr oss ra- raa rab raf rai rak ran rao rar ras rba rbb rbf rbi rbk rbn rbo rbr rbs rfa rfb rff rfi rfk rfn rfo rfr rfs ria rib rif rii rik rin rio rir ris rkb rkf rkk rko rks rna rnb rni rnn rno rnr rns roa rob rof roi rok ron roo ror ros rra rrb rrf rri rrk rrn rrr rrs rsa rsb rsf rsi rsk rsn rso rsr rss saa sab saf sai sak san sao sar sas sba sbb sbf sbi sbk sbn sbo sbr sbs sfa sfb sff sfi sfk sfn sfo sfr sfs sia sib sif sii sik sin sio sir sis sk- ska skb skf ski skk sko skr sks sna snb snf sni snk snn sno snr sns soa sob sof soi sok son soo sor sos sr- sra srb srf sri srk srn sro srr srs ss- ssa ssb ssf ssi ssk ssn sso ssr sss