a-a a-b a-i aaa aab aai aan aas ab- aba abb abi abn abs ai- aia aib aii ain ais an- ana anb ani ann ans as- asa asb asi asn ass baa bab bai ban bas bba bbb bbi bbn bbs bi- bia bib bii bin bis bna bnb bni bnn bns bsa bsb bsi bsn bss ia- iaa iab iai ian ias iba ibb ibi ibn ibs iia iib iii iin iis in- ina inb ini inn ins is- isa isb isi isn iss n-i naa nab nai nan nas nba nbb nbi nbn nbs nia nib nii nin nis nna nnb nni nnn nns nsa nsb nsi nsn nss saa sab sai san sas sba sbb sbi sbn sbs sia sib sii sin sis sna snb sni snn sns ss- ssa ssb ssi ssn sss