a-a a-b aaa aab aak aan aao aas aay ab- aba abb abk abn abo abs aby aka akb akk akn ako aks an- ana anb ank ann ano ans any aoa aob aok aon aoo aos as- asa asb ask asn aso ass asy ay- aya ayk ayn ayo ays baa bab bak ban bao bas bay bba bbb bbk bbn bbo bbs bby bka bkb bkk bkn bko bks bna bnb bnk bnn bno bns boa bob bok bon boo bos boy bsa bsb bsk bsn bso bss bsy by- bya byk byn byo bys ka- kaa kab kak kan kao kas kay kba kbb kbk kbn kbo kbs kkb kkk kkn kks kky kn- kna knk knn kno koa kob kok kon koo kos koy ksa ksb ksk ksn kso kss kya kyn kyo kys naa nab nak nan nao nas nay nba nbb nbk nbn nbo nbs nka nkk nkn nko nks nky nna nnb nnk nnn nno nns no- noa nob nok non noo nos noy nsa nsb nsk nsn nso nss nsy nya nyk nyn nyo nys nyy oaa oab oak oan oao oas ob- oba obb obk obn obo obs oby oka okb okk oko oks on- ona onb onk onn ono ons ony oo- ooa oob ook oon ooo oos os- osa osb osk osn oso oss oya oyo oys saa sab sak san sao sas say sba sbb sbk sbn sbo sbs sby sk- ska skb skk sko sks sky sna snb snk snn sno sns sny soa sob sok son soo sos soy ss- ssa ssb ssk ssn sso sss sy- sya syb syk syn sys yaa yab yak yan yao yas yay ybs yby yka ykk ykn yna ynk ynn yns yny yob yok yon yoo yos yoy ysa ysb ysk yso yss ysy yyb yys yyy