a-a a-b a-c aaa aab aac aad aaf aak aao aay ab- aba abb abc abd abf abk abo aby ac- aca acb acc acd acf ack aco acy ad- ada adb adc add adf adk ado ady af- afa afb afc afd aff afk afo afy aka akb akc akd akk ako aoa aob aoc aod aof aok aoo ay- aya ayc ayd ayf ayk ayo baa bab bac bad baf bak bao bay bba bbb bbc bbd bbf bbk bbo bby bca bcb bcc bcd bcf bck bco bcy bda bdb bdc bdd bdf bdk bdo bdy bfa bfb bfc bfd bff bfo bfy bka bkb bkc bkf bkk bko boa bob boc bod bof bok boo boy by- bya byc byd byf byk byo c-- caa cab cac cad caf cak cao cay cba cbb cbc cbd cbf cbk cbo cby cca ccb ccc ccd ccf cck cco cda cdb cdc cdd cdf cdk cdo cdy cfa cfb cfc cfd cff cfk cfo cka ckb ckc ckd cko cky co- coa cob coc cod cof cok coo coy cya cyb cyc cyd cyf cyk cyo daa dab dac dad daf dak dao day dba dbb dbc dbd dbf dbk dbo dby dca dcb dcc dcd dcf dck dco dda ddb ddc ddd ddf ddk ddo ddy dfa dfb dfc dfd dff dfk dfo dka dkb dkc dkk dko doa dob doc dod dof dok doo doy dy- dya dyb dyc dyd dyk dyo dyy faa fab fac fad faf fak fao fay fba fbb fbc fbd fbf fbk fbo fca fcb fcc fcd fcf fck fco fcy fda fdb fdc fdd fdf fdk fdo ffa ffc ffd fff ffk ffo ffy fka fkb fkc fkf fkk foa fob foc fof fok foo foy fy- fya fyb fyc fyk fyo ka- kaa kab kac kad kaf kak kao kay kba kbb kbc kbd kbf kbk kbo kca kcb kcc kcd kck kda kdb kdc kdf kdk kdo kdy kfa kfc kfd kff kfo kkb kkc kkk kky koa kob koc kod kof kok koo koy kya kyc kyd kyo oaa oab oac oad oaf oak oao ob- oba obb obc obd obf obk obo oby oc- oca ocb occ ocd ocf ock oco oda odb odc odd odf odo of- ofa ofb ofc ofd off ofo oka okb okc okd okk oko oo- ooa oob ooc ood oof ook ooo oya oyd oyo yaa yab yac yad yaf yak yao yay ybc ybf yby yca ycc ycd ycf yco ycy yda ydo ydy yfa yfc yfd yff yka ykk yob yoc yod yof yok yoo yoy yyb yyc yyf yyy