a-a a-b a-i aaa aab aaf aai aan aas ab- aba abb abf abi abn abs af- afa afb aff afi afn afs ai- aia aib aif aii ain ais an- ana anb anf ani ann ans as- asa asb asf asi asn ass baa bab baf bai ban bas bba bbb bbf bbi bbn bbs bfa bfb bff bfi bfn bfs bi- bia bib bif bii bin bis bna bnb bnf bni bnn bns bsa bsb bsf bsi bsn bss faa fab faf fai fan fas fba fbb fbf fbi fbn fbs ffa fff ffi ffn ffs fia fib fif fii fin fis fna fnb fnf fni fnn fns fsa fsb fsf fsi fsn fss i-f ia- iaa iab iaf iai ian ias iba ibb ibf ibi ibn ibs ifa ifb iff ifi ifn ifs iia iib iif iii iin iis in- ina inb inf ini inn ins is- isa isb isf isi isn iss n-i naa nab naf nai nan nas nba nbb nbf nbi nbn nbs nfa nfb nff nfi nfn nfs nia nib nif nii nin nis nna nnb nnf nni nnn nns nsa nsb nsf nsi nsn nss saa sab saf sai san sas sba sbb sbf sbi sbn sbs sfa sfb sff sfi sfn sfs sia sib sif sii sin sis sna snb snf sni snn sns ss- ssa ssb ssf ssi ssn sss