a-a a-b a-i aaa aab aai aak aan aao aas ab- aba abb abi abk abn abo abs ai- aia aib aii aik ain aio ais aka akb aki akk akn ako aks an- ana anb ani ank ann ano ans aoa aob aoi aok aon aoo aos as- asa asb asi ask asn aso ass baa bab bai bak ban bao bas bba bbb bbi bbk bbn bbo bbs bi- bia bib bii bik bin bio bis bka bkb bkk bkn bko bks bna bnb bni bnk bnn bno bns boa bob boi bok bon boo bos bsa bsb bsi bsk bsn bso bss ia- iaa iab iai ian iao ias iba ibb ibi ibk ibn ibo ibs iia iib iii iin iio iis ika ikb iki ikk iko iks in- ina inb ini ink inn ino ins io- ioa iob ioi ion ioo ios is- isa isb isi isk isn iso iss ka- kaa kab kai kak kan kao kas kba kbb kbi kbk kbn kbo kbs kia kib kii kik kin kio kis kkb kki kkk kkn kks kn- kna kni knk knn kno koa kob koi kok kon koo kos ksa ksb ksi ksk ksn kso kss n-i naa nab nai nak nan nao nas nba nbb nbi nbk nbn nbo nbs nia nib nii nik nin nio nis nka nki nkk nkn nko nks nna nnb nni nnk nnn nno nns no- noa nob noi nok non noo nos nsa nsb nsi nsk nsn nso nss o-i oaa oab oai oak oan oao oas ob- oba obb obi obk obn obo obs oia oib oii oik oin oio ois oka okb oki okk oko oks on- ona onb oni onk onn ono ons oo- ooa oob ooi ook oon ooo oos os- osa osb osi osk osn oso oss saa sab sai sak san sao sas sba sbb sbi sbk sbn sbo sbs sia sib sii sik sin sio sis sk- ska skb ski skk sko sks sna snb sni snk snn sno sns soa sob soi sok son soo sos ss- ssa ssb ssi ssk ssn sso sss