a-a a-b a-c aaa aab aac aaf aak aao aas ab- aba abb abc abf abk abo abs ac- aca acb acc acf ack aco acs af- afa afb afc aff afk afo afs aka akb akc akk ako aks aoa aob aoc aof aok aoo aos as- asa asb asc asf ask aso ass baa bab bac baf bak bao bas bba bbb bbc bbf bbk bbo bbs bca bcb bcc bcf bck bco bcs bfa bfb bfc bff bfo bfs bka bkb bkc bkf bkk bko bks boa bob boc bof bok boo bos bsa bsb bsc bsf bsk bso bss c-- caa cab cac caf cak cao cas cba cbb cbc cbf cbk cbo cbs cca ccb ccc ccf cck cco ccs cfa cfb cfc cff cfk cfo cfs cka ckb ckc cko cks co- coa cob coc cof cok coo cos csa csb csc csf csk cso css faa fab fac faf fak fao fas fba fbb fbc fbf fbk fbo fbs fca fcb fcc fcf fck fco fcs ffa ffc fff ffk ffo ffs fka fkb fkc fkf fkk foa fob foc fof fok foo fos fsa fsb fsc fsf fsk fso fss ka- kaa kab kac kaf kak kao kas kba kbb kbc kbf kbk kbo kbs kca kcb kcc kck kcs kfa kfc kff kfo kfs kkb kkc kkk kks koa kob koc kof kok koo kos ksa ksb ksc ksf ksk kso kss oaa oab oac oaf oak oao oas ob- oba obb obc obf obk obo obs oc- oca ocb occ ocf ock oco ocs of- ofa ofb ofc off ofo ofs oka okb okc okk oko oks oo- ooa oob ooc oof ook ooo oos os- osa osb osc osf osk oso oss saa sab sac saf sak sao sas sba sbb sbc sbf sbk sbo sbs sca scb scc scf sck sco scs sfa sfb sfc sff sfk sfo sfs sk- ska skb skc skf skk sko sks soa sob soc sof sok soo sos ss- ssa ssb ssc ssf ssk sso sss

a-ak a-ok aaaa aaab aaac aaaf aaas aaba aabb aabc aaca aacb aacc aacf aack aaco aacs aafa aafb aafc aaff aaka aaoo aasa aasc aasf aass abaa abab abac abaf abak abas abb- abba abbb abbo abbs abca abcb abcc abcf abcs abff aboa abob abof abok aboo abos abs- absa absf abss acaa acab acac acas acba acca accc accf acco accs acfc acfs acks acoa acos acsa acsc acss afaa afak afao afbs afca afcb afcc afcs affa affc affo affs afka afoa afoo afsa afsb afsc akaa akao akas akca akka akko akok akos aksa aoba aoca aocs aoks aoss asaa asab asac asaf asak asao asas asba asbo asc- asca ascb ascc asco asfa aska asko asks asob asoc asof asok asos assa assc assk asso asss baaa baaf baak baas baba babb babo babs bac- baca bacc back baco bacs bafc baff bafo bak- baka bako baks baos basa basc basf bask baso bass bbas bbbb bbbs bbfc bcaa bcas bcbc bcbs bcca bccc bccs bcfc bcof bcos bcsa bcsc bcss bfas bfca bfcs bffs boab boac boak boas boba bobb bobo bobs boca bock boco bocs bofa boff bofs boka boko boks boob booc boof book boos bosa bosc bosk boso boss bsaa bsac bsas bscs bsfa bsfc bsff bsfs bsos bssc c-bo caaa caab caac caaf caas caba cabf cabo cabs cac- caca cacc cack caco cafa cafb cafc caff cafs caka caos casa casb casc cask caso cass cbac cbbc cbbs cbca cbcc cbcs cbfb cbfc cbka cbko cbsa cbsc ccaa ccab ccac ccaf ccas ccba ccbc ccca cccb cccc cccf cccs ccfa ccfc ccff ccob ccoc ccsa ccsf ccss cfaa cfab cfac cfao cfbc cfbs cfca cfcb cfcf cfco cfcs cffb cfoa cfos cfsa ckac ckbc ckck ckco ckcs ckoa ckob ckoc ckoo ckos cksa cksb ckso coak coas coba cobb cobo cobs coca cock coco cofc coff cofs cok- coka coko coob coof cook coos cosa cosc coso coss csaa csab csac csak csao csas csbf cscb cscc cscf csco cscs csfc cska csks csob csos cssa f--k faaa faac faas faba fabo fabs faca facc fack facs fafa fafc faff fafo fako fasa fasc faso fass fcab fcas fcba fcbs fcca fccf fcsc ffcc ffff ffsa ffss fkab foaf foak foba fobs foca fock foco focs fofo foof fook foos fosa fosb foso foss fsas fscb fscc fsck fsfo fssa fssc fssf k-os kaaa kaab kaaf kaak kaas kaba kabb kabc kabf kabo kacb kacc kaco kacs kafa kafc kaff kafs kaka kakc kakk kako kaks kaoa kaoc kaok kaos kas- kasa kasb kasc kasf kask kaso kass kbaa kbab kbac kbak kbas kbba kbbb kbbc kbbf kbbk kbbo kbbs kbca kbcb kbck kbco kbcs kbfb kbfc kbff kbfk kbfo kbfs kbkb kbkf kbkk kbko kboa kbob kboc kbok kboo kbos kbsa kbsb kbsk kbso kbss kcaa kcab kcac kcas kcba kcbc kcbf kcbk kcbs kcca kccb kccc kcck kcfa kcfb kcfc kcfo kckc kckf kckk kcko kcob kcof kcos kcsa kcsb kcsc kcsf kcss kfab kfac kfbc kfbk kfcf kfco kfcs kffa kffb kfff kffk kfka kfkb kfok kfoo kfsa kfsk kkaa kkac kkba kkbb kkbo kkbs kkcb kkck kkco kkcs kkfs kkkk kkoa kkob kkoo kksa kksf kkss koab koac koak koas koba kobb kobc kobk kobo kobs koca kocb kocf kock kocs kofa kofc koff kofk kofo koka kokb kokc kokf kokk koko koks koob kooc kook kooo koos kos- kosa kosb kosc kosf koso koss ksab ksac ksaf ksak ksas ksba ksbc ksbs ksca kscb ksck ksco kscs ksfa ksfb ksfc ksfo kska kskb kskf kskk ksko ksks ksob ksoc ksof ksok ksoo ksos kssa ksso ksss oafc oafo oafs oaks oasc oass obak obas obba obbo obkb obok obos obss ocab ocac ocak ocas ocbc occa occc ocfa ocks ocos ocsa ofas off- offa offc offo offs okak okas okka okko okok oksa okso ooaa ooak ooba ooff oofs