a-a a-b aaa aab aaf aan aao aas aay ab- aba abb abf abn abo abs aby af- afa afb aff afn afo afs afy an- ana anb anf ann ano ans any aoa aob aof aon aoo aos as- asa asb asf asn aso ass asy ay- aya ayf ayn ayo ays baa bab baf ban bao bas bay bba bbb bbf bbn bbo bbs bby bfa bfb bff bfn bfo bfs bfy bna bnb bnf bnn bno bns boa bob bof bon boo bos boy bsa bsb bsf bsn bso bss bsy by- bya byf byn byo bys faa fab faf fan fao fas fay fba fbb fbf fbn fbo fbs ffa fff ffn ffo ffs ffy fna fnb fnf fnn fns foa fob fof fon foo fos foy fsa fsb fsf fsn fso fss fy- fya fyb fyn fyo naa nab naf nan nao nas nay nba nbb nbf nbn nbo nbs nfa nfb nff nfn nfo nfs nna nnb nnf nnn nno nns no- noa nob nof non noo nos noy nsa nsb nsf nsn nso nss nsy nya nyf nyn nyo nys nyy oaa oab oaf oan oao oas ob- oba obb obf obn obo obs oby of- ofa ofb off ofn ofo ofs on- ona onb onf onn ono ons ony oo- ooa oob oof oon ooo oos os- osa osb osf osn oso oss oya oyo oys saa sab saf san sao sas say sba sbb sbf sbn sbo sbs sby sfa sfb sff sfn sfo sfs sna snb snf snn sno sns sny soa sob sof son soo sos soy ss- ssa ssb ssf ssn sso sss sy- sya syb syn sys yaa yab yaf yan yao yas yay ybf ybs yby yfa yff yfs yna ynn yns yny yob yof yon yoo yos yoy ysa ysb yso yss ysy yyb yyf yys yyy