a-a a-b a-i aaa aab aaf aai aak aan aar aas ab- aba abb abf abi abk abn abr abs af- afa afb aff afi afk afn afr afs ai- aia aib aif aii aik ain air ais aka akb aki akk akn akr aks an- ana anb anf ani ank ann anr ans ar- ara arb arf ari ark arn arr ars as- asa asb asf asi ask asn asr ass baa bab baf bai bak ban bar bas bba bbb bbf bbi bbk bbn bbr bbs bfa bfb bff bfi bfn bfr bfs bi- bia bib bif bii bik bin bir bis bka bkb bkf bkk bkn bkr bks bna bnb bnf bni bnk bnn bnr bns bra brb brf bri brk brn brr brs bsa bsb bsf bsi bsk bsn bsr bss faa fab faf fai fak fan far fas fba fbb fbf fbi fbk fbn fbr fbs ffa fff ffi ffk ffn ffr ffs fia fib fif fii fik fin fir fis fka fkb fkf fki fkk fna fnb fnf fni fnk fnn fnr fns fra frb frf fri frk frn frr frs fsa fsb fsf fsi fsk fsn fsr fss i-f ia- iaa iab iaf iai ian iar ias iba ibb ibf ibi ibk ibn ibr ibs ifa ifb iff ifi ifn ifr ifs iia iib iif iii iin iir iis ika ikb ikf iki ikk ikr iks in- ina inb inf ini ink inn inr ins ir- ira irb irf iri irk irn irr irs is- isa isb isf isi isk isn isr iss ka- kaa kab kaf kai kak kan kar kas kba kbb kbf kbi kbk kbn kbr kbs kfa kff kfi kfs kia kib kif kii kik kin kir kis kkb kki kkk kkn kkr kks kn- kna knf kni knk knn knr kra krf kri krk krn krr krs ksa ksb ksf ksi ksk ksn ksr kss n-i naa nab naf nai nak nan nar nas nba nbb nbf nbi nbk nbn nbr nbs nfa nfb nff nfi nfk nfn nfr nfs nia nib nif nii nik nin nir nis nka nkf nki nkk nkn nkr nks nna nnb nnf nni nnk nnn nns nra nrb nrf nri nrk nrn nrr nrs nsa nsb nsf nsi nsk nsn nsr nss ra- raa rab raf rai rak ran rar ras rba rbb rbf rbi rbk rbn rbr rbs rfa rfb rff rfi rfk rfn rfr rfs ria rib rif rii rik rin rir ris rkb rkf rkk rks rna rnb rni rnn rnr rns rra rrb rrf rri rrk rrn rrr rrs rsa rsb rsf rsi rsk rsn rsr rss saa sab saf sai sak san sar sas sba sbb sbf sbi sbk sbn sbr sbs sfa sfb sff sfi sfk sfn sfr sfs sia sib sif sii sik sin sir sis sk- ska skb skf ski skk skr sks sna snb snf sni snk snn snr sns sr- sra srb srf sri srk srn srr srs ss- ssa ssb ssf ssi ssk ssn ssr sss