a-a a-b a-i aaa aab aai aak aao aas aay ab- aba abb abi abk abo abs aby ai- aia aib aii aik aio ais aiy aka akb aki akk ako aks aoa aob aoi aok aoo aos as- asa asb asi ask aso ass asy ay- aya ayi ayk ayo ays baa bab bai bak bao bas bay bba bbb bbi bbk bbo bbs bby bi- bia bib bii bik bio bis biy bka bkb bkk bko bks boa bob boi bok boo bos boy bsa bsb bsi bsk bso bss bsy by- bya byi byk byo bys ia- iaa iab iai iao ias iba ibb ibi ibk ibo ibs iby iia iib iii iio iis ika ikb iki ikk iko iks io- ioa iob ioi ioo ios is- isa isb isi isk iso iss isy iya iyo iys iyy ka- kaa kab kai kak kao kas kay kba kbb kbi kbk kbo kbs kia kib kii kik kio kis kkb kki kkk kks kky koa kob koi kok koo kos koy ksa ksb ksi ksk kso kss kya kyo kys o-i oaa oab oai oak oao oas ob- oba obb obi obk obo obs oby oia oib oii oik oio ois oka okb oki okk oko oks oo- ooa oob ooi ook ooo oos os- osa osb osi osk oso oss oya oyi oyo oys saa sab sai sak sao sas say sba sbb sbi sbk sbo sbs sby sia sib sii sik sio sis sk- ska skb ski skk sko sks sky soa sob soi sok soo sos soy ss- ssa ssb ssi ssk sso sss sy- sya syb syi syk sys yaa yab yai yak yao yas yay ybi ybs yby yii yio yis yka yki ykk yob yoi yok yoo yos yoy ysa ysb ysi ysk yso yss ysy yyb yys yyy