a-a a-b aaa aab aaf aag aao aas aay ab- aba abb abf abg abo abs aby af- afa afb aff afg afo afs afy ag- aga agb agf agg ago ags agy aoa aob aof aog aoo aos as- asa asb asf asg aso ass asy ay- aya ayf ayo ays baa bab baf bag bao bas bay bba bbb bbf bbg bbo bbs bby bfa bfb bff bfg bfo bfs bfy bga bgb bgf bgg bgo bgs boa bob bof bog boo bos boy bsa bsb bsf bsg bso bss bsy by- bya byf byg byo bys faa fab faf fag fao fas fay fba fbb fbf fbg fbo fbs ffa fff ffg ffo ffs ffy fga fgb fgf fgg fgs foa fob fof fog foo fos foy fsa fsb fsf fsg fso fss fy- fya fyb fyo gaa gab gaf gag gao gas gay gba gbf gbg gbo gbs gby gfa gfb gff gfo gfs gfy gga ggb ggg ggo ggs goa gob gof gog goo gos goy gsa gsb gsf gsg gso gss gy- gya gyb gyf gyo gys oaa oab oaf oag oao oas ob- oba obb obf obg obo obs oby of- ofa ofb off ofg ofo ofs oga ogf ogg ogo ogs ogy oo- ooa oob oof oog ooo oos os- osa osb osf osg oso oss oya oyo oys saa sab saf sag sao sas say sba sbb sbf sbg sbo sbs sby sfa sfb sff sfg sfo sfs sga sgb sgf sgg sgo sgs soa sob sof sog soo sos soy ss- ssa ssb ssf ssg sso sss sy- sya syb syg sys yaa yab yaf yag yao yas yay ybf ybg ybs yby yfa yff yfs yga ygo yob yof yog yoo yos yoy ysa ysb ysg yso yss ysy yyb yyf yyg yys yyy