a-a a-b a-c aaa aab aac aan aao aas aay ab- aba abb abc abn abo abs aby ac- aca acb acc acn aco acs acy an- ana anb anc ann ano ans any aoa aob aoc aon aoo aos as- asa asb asc asn aso ass asy ay- aya ayc ayn ayo ays baa bab bac ban bao bas bay bba bbb bbc bbn bbo bbs bby bca bcb bcc bcn bco bcs bcy bna bnb bnc bnn bno bns boa bob boc bon boo bos boy bsa bsb bsc bsn bso bss bsy by- bya byc byn byo bys c-- caa cab cac can cao cas cay cba cbb cbc cbn cbo cbs cby cca ccb ccc ccn cco ccs cn- cna cnb cnc cnn cno cns cny co- coa cob coc con coo cos coy csa csb csc csn cso css csy cya cyb cyc cyn cyo cys naa nab nac nan nao nas nay nba nbb nbc nbn nbo nbs nca ncb ncc ncn nco ncs nna nnb nnc nnn nno nns no- noa nob noc non noo nos noy nsa nsb nsc nsn nso nss nsy nya nyc nyn nyo nys nyy oaa oab oac oan oao oas ob- oba obb obc obn obo obs oby oc- oca ocb occ ocn oco ocs on- ona onb onc onn ono ons ony oo- ooa oob ooc oon ooo oos os- osa osb osc osn oso oss oya oyo oys saa sab sac san sao sas say sba sbb sbc sbn sbo sbs sby sca scb scc scn sco scs sna snb snc snn sno sns sny soa sob soc son soo sos soy ss- ssa ssb ssc ssn sso sss sy- sya syb syc syn sys yaa yab yac yan yao yas yay ybc ybs yby yca ycc yco ycs ycy yna ynn yns yny yob yoc yon yoo yos yoy ysa ysb ysc yso yss ysy yyb yyc yys yyy