-al a-a a-b a-c aaa aab aac aaf aak aal aas ab- aba abb abc abf abk abl abs ac- aca acb acc acf ack acl acs af- afa afb afc aff afk afl afs aka akb akc akk akl aks al- ala alb alc alf alk all als as- asa asb asc asf ask asl ass baa bab bac baf bak bal bas bba bbb bbc bbf bbk bbl bbs bca bcb bcc bcf bck bcl bcs bfa bfb bfc bff bfl bfs bka bkb bkc bkf bkk bkl bks bla blb blc blf blk bll bls bsa bsb bsc bsf bsk bsl bss c-- caa cab cac caf cak cal cas cba cbb cbc cbf cbk cbl cbs cca ccb ccc ccf cck ccl ccs cfa cfb cfc cff cfk cfl cfs cka ckb ckc cks cl- cla clb clc clf clk cll cls csa csb csc csf csk csl css faa fab fac faf fak fal fas fba fbb fbc fbf fbk fbl fbs fca fcb fcc fcf fck fcl fcs ffa ffc fff ffk ffl ffs fka fkb fkc fkf fkk fkl fla flb flc flf fll fls fsa fsb fsc fsf fsk fsl fss ka- kaa kab kac kaf kak kal kas kba kbb kbc kbf kbk kbl kbs kca kcb kcc kck kcl kcs kfa kfc kff kfs kkb kkc kkk kkl kks kl- kla klb klc klf kls ksa ksb ksc ksf ksk ksl kss la- laa lab lac laf lak lal las lba lbb lbc lbf lbk lbl lbs lca lcb lcc lcf lck lcl lcs lfa lfb lfc lff lfk lfl lfs lka lkb lkl lks lla llb llc llf llk lll lls lsa lsb lsc lsf lsk lsl lss saa sab sac saf sak sal sas sba sbb sbc sbf sbk sbl sbs sca scb scc scf sck scl scs sfa sfb sfc sff sfk sfl sfs sk- ska skb skc skf skk skl sks sla slb slc slf slk sll sls ss- ssa ssb ssc ssf ssk ssl sss

a-ak aaaa aaab aaac aaaf aaal aaas aaba aabb aabc aabl aaca aacb aacc aacf aack aacl aacs aafa aafb aafc aaff aafl aaka aala aalc aall aals aasa aasc aasf aass abaa abab abac abaf abak abal abas abb- abba abbb abbs abca abcb abcc abcf abcl abcs abff abla abls abs- absa absf absl abss acaa acab acac acas acba acbl acca accc accf accs acfc acfl acfs acks acla aclc acls acsa acsc acsl acss afaa afak afbs afca afcb afcc afcs affa affc affs afka afla aflc afsa afsb afsc akaa akal akas akca akka aksa alaa alac alak alal alas alb- alba albc albs alca alcc alcs alfa alfs alk- alka alkb all- alla alll alls alsa alsc asaa asab asac asaf asak asal asas asba asc- asca ascb ascc ascl asfa aska asks asla assa assc assk assl asss baaa baaf baak baal baas baba babb babs bac- baca bacc back bacs bafc baff bak- baka bakl baks bala balc balf balk ball bals basa basc basf bask bass bbas bbbb bbbs bbfc bblb bbls bcaa bcas bcbc bcbs bcca bccc bccl bccs bcfc bcsa bcsc bcsl bcss bfas bfca bfcs bffl bffs blaa blab blac blak blas blfc blkb blls blss bsaa bsac bsas bscs bsfa bsfc bsff bsfs bslc bssc caaa caab caac caaf caal caas caba cabf cabs cac- caca cacc cack cafa cafb cafc caff cafl cafs caka cala calc calf calk call cals casa casb casc cask casl cass cbac cbal cbbc cbbs cbca cbcc cbcl cbcs cbfb cbfc cbka cbkl cblb cblc cbsa cbsc ccaa ccab ccac ccaf ccas ccba ccbc ccca cccb cccc cccf cccl cccs ccfa ccfc ccff ccfl ccla cclc ccls ccsa ccsf ccsl ccss cfaa cfab cfac cfbc cfbs cfca cfcb cfcf cfcl cfcs cffb cfls cfsa cfsl ckac ckbc ckck ckcl ckcs cklf cksa cksb cksl clab claf clas clsa clsc csaa csab csac csak csas csbf cscb cscc cscf cscl cscs csfc cska csks csla cssa f--k faaa faac faas faba fabs faca facc fack facs fafa fafc faff fala falc falk fall fals fasa fasc fass fbla fcab fcal fcas fcba fcbs fcca fccf fcsc fcsl ffcc ffff ffsa ffss fkab flab flac flak flcl fsas fscb fscc fsck fssa fssc fssf kaaa kaab kaaf kaak kaal kaas kaba kabb kabc kabf kacb kacc kacl kacs kafa kafc kaff kafs kaka kakc kakk kaks kala kalb kalc kalf kalk kall kals kas- kasa kasb kasc kasf kask kasl kass kbaa kbab kbac kbak kbal kbas kbba kbbb kbbc kbbf kbbk kbbl kbbs kbca kbcb kbck kbcl kbcs kbfb kbfc kbff kbfk kbfl kbfs kbkb kbkf kbkk kbkl kbla kblb kblf kbll kbls kbsa kbsb kbsk kbss kcaa kcab kcac kcal kcas kcba kcbc kcbf kcbk kcbl kcbs kcca kccb kccc kcck kccl kcfa kcfb kcfc kcfl kckc kckf kckk kckl kcla kclc kclf kclk kcll kcls kcsa kcsb kcsc kcsf kcss kfab kfac kfal kfbc kfbk kfcf kfcs kffa kffb kfff kffk kfka kfkb kfla kflb kflc kflf kfll kfls kfsa kfsk kkaa kkac kkal kkba kkbb kkbl kkbs kkcb kkck kkcl kkcs kkfs kkkk kklb kklc kklf kkll kkls kksa kksf kkss klaa klab klac klaf klak klal klas klbb klbc klbf klbl klbs klca klcb klcc klck klcl klcs klfa klfc klff klka klkc klkk klkl klks klla kllb kllc kllk klls klsa klsc klsf ksab ksac ksaf ksak ksal ksas ksba ksbc ksbl ksbs ksca kscb ksck kscl kscs ksfa ksfb ksfc kska kskb kskf kskk ksks ksla kslb kslc kslk ksll kssa kssl ksss laaa laac laak laal laas laba labs laca lacc lack lacl lacs lafb lafc laff laka laks lala lall lasa lask lass lbcc lbsc lcac lcbc lcca lccc lccs lcfc lcls lcsc lfca lfcc lkab lkal lkfs llbs llcc llcs llks lllc llll lscb lscs lsfc lsla lssa sa-c saab saac saaf saak saal saas saba sabb sabc sabs saca sacc sack sacs