a-a a-b a-i aaa aab aaf aai aak aan aas ab- aba abb abf abi abk abn abs af- afa afb aff afi afk afn afs ai- aia aib aif aii aik ain ais aka akb aki akk akn aks an- ana anb anf ani ank ann ans as- asa asb asf asi ask asn ass baa bab baf bai bak ban bas bba bbb bbf bbi bbk bbn bbs bfa bfb bff bfi bfn bfs bi- bia bib bif bii bik bin bis bka bkb bkf bkk bkn bks bna bnb bnf bni bnk bnn bns bsa bsb bsf bsi bsk bsn bss faa fab faf fai fak fan fas fba fbb fbf fbi fbk fbn fbs ffa fff ffi ffk ffn ffs fia fib fif fii fik fin fis fka fkb fkf fki fkk fna fnb fnf fni fnk fnn fns fsa fsb fsf fsi fsk fsn fss i-f ia- iaa iab iaf iai ian ias iba ibb ibf ibi ibk ibn ibs ifa ifb iff ifi ifn ifs iia iib iif iii iin iis ika ikb ikf iki ikk iks in- ina inb inf ini ink inn ins is- isa isb isf isi isk isn iss ka- kaa kab kaf kai kak kan kas kba kbb kbf kbi kbk kbn kbs kfa kff kfi kfs kia kib kif kii kik kin kis kkb kki kkk kkn kks kn- kna knf kni knk knn ksa ksb ksf ksi ksk ksn kss n-i naa nab naf nai nak nan nas nba nbb nbf nbi nbk nbn nbs nfa nfb nff nfi nfk nfn nfs nia nib nif nii nik nin nis nka nkf nki nkk nkn nks nna nnb nnf nni nnk nnn nns nsa nsb nsf nsi nsk nsn nss saa sab saf sai sak san sas sba sbb sbf sbi sbk sbn sbs sfa sfb sff sfi sfk sfn sfs sia sib sif sii sik sin sis sk- ska skb skf ski skk sks sna snb snf sni snk snn sns ss- ssa ssb ssf ssi ssk ssn sss