a-a a-b a-i aaa aab aai aan aao aas ab- aba abb abi abn abo abs ai- aia aib aii ain aio ais an- ana anb ani ann ano ans aoa aob aoi aon aoo aos as- asa asb asi asn aso ass baa bab bai ban bao bas bba bbb bbi bbn bbo bbs bi- bia bib bii bin bio bis bna bnb bni bnn bno bns boa bob boi bon boo bos bsa bsb bsi bsn bso bss ia- iaa iab iai ian iao ias iba ibb ibi ibn ibo ibs iia iib iii iin iio iis in- ina inb ini inn ino ins io- ioa iob ioi ion ioo ios is- isa isb isi isn iso iss n-i naa nab nai nan nao nas nba nbb nbi nbn nbo nbs nia nib nii nin nio nis nna nnb nni nnn nno nns no- noa nob noi non noo nos nsa nsb nsi nsn nso nss o-i oaa oab oai oan oao oas ob- oba obb obi obn obo obs oia oib oii oin oio ois on- ona onb oni onn ono ons oo- ooa oob ooi oon ooo oos os- osa osb osi osn oso oss saa sab sai san sao sas sba sbb sbi sbn sbo sbs sia sib sii sin sio sis sna snb sni snn sno sns soa sob soi son soo sos ss- ssa ssb ssi ssn sso sss