-al a-a a-b a-c aaa aab aac aad aaf aak aal aas ab- aba abb abc abd abf abk abl abs ac- aca acb acc acd acf ack acl acs ad- ada adb adc add adf adk adl ads af- afa afb afc afd aff afk afl afs aka akb akc akd akk akl aks al- ala alb alc ald alf alk all als as- asa asb asc asd asf ask asl ass baa bab bac bad baf bak bal bas bba bbb bbc bbd bbf bbk bbl bbs bca bcb bcc bcd bcf bck bcl bcs bda bdb bdc bdd bdf bdk bdl bds bfa bfb bfc bfd bff bfl bfs bka bkb bkc bkf bkk bkl bks bla blb blc bld blf blk bll bls bsa bsb bsc bsd bsf bsk bsl bss c-- caa cab cac cad caf cak cal cas cba cbb cbc cbd cbf cbk cbl cbs cca ccb ccc ccd ccf cck ccl ccs cda cdb cdc cdd cdf cdk cdl cds cfa cfb cfc cfd cff cfk cfl cfs cka ckb ckc ckd cks cl- cla clb clc cld clf clk cll cls csa csb csc csd csf csk csl css daa dab dac dad daf dak dal das dba dbb dbc dbd dbf dbk dbl dbs dca dcb dcc dcd dcf dck dcl dcs dda ddb ddc ddd ddf ddk ddl dds dfa dfb dfc dfd dff dfk dfl dfs dka dkb dkc dkk dkl dks dl- dla dlb dlc dld dlf dlk dll dls dsa dsb dsc dsd dsf dsk dsl dss faa fab fac fad faf fak fal fas fba fbb fbc fbd fbf fbk fbl fbs fca fcb fcc fcd fcf fck fcl fcs fda fdb fdc fdd fdf fdk fdl fds ffa ffc ffd fff ffk ffl ffs fka fkb fkc fkf fkk fkl fla flb flc fld flf fll fls fsa fsb fsc fsd fsf fsk fsl fss ka- kaa kab kac kad kaf kak kal kas kba kbb kbc kbd kbf kbk kbl kbs kca kcb kcc kcd kck kcl kcs kda kdb kdc kdf kdk kdl kds kfa kfc kfd kff kfs kkb kkc kkk kkl kks kl- kla klb klc kld klf kls ksa ksb ksc ksd ksf ksk ksl kss la- laa lab lac lad laf lak lal las lba lbb lbc lbd lbf lbk lbl lbs lca lcb lcc lcd lcf lck lcl lcs lda ldb ldc ldd ldf ldk ldl lds lfa lfb lfc lfd lff lfk lfl lfs lka lkb lkl lks lla llb llc lld llf llk lll lls lsa lsb lsc lsd lsf lsk lsl lss saa sab sac sad saf sak sal sas sba sbb sbc sbd sbf sbk sbl sbs sca scb scc scd scf sck scl scs sda sdb sdc sdd sdf sdk sdl sds sfa sfb sfc sfd sff sfk sfl sfs sk- ska skb skc skd skf skk skl sks sla slb slc sld slf slk sll sls ss- ssa ssb ssc ssd ssf ssk ssl sss

a-ak aaaa aaab aaac aaad aaaf aaal aaas aaba aabb aabc aabd aabl aaca aacb aacc aacd aacf aack aacl aacs aada aadc aads aafa aafb aafc aafd aaff aafl aaka aala aalc aald aall aals aasa aasc aasd aasf aass abaa abab abac abad abaf abak abal abas abb- abba abbb abbs abca abcb abcc abcd abcf abcl abcs abda abff abla abls abs- absa absd absf absl abss acaa acab acac acad acas acba acbl acca accc accd accf accs acda acdb acdc acdf acds acfc acfd acfl acfs ackd acks acla aclc acls acsa acsc acsd acsl acss adaa adab adac adad adak adal adas adba adbc adcc adcs adda addc addd addl adds adfa adfc adfl adfs adls adsa adsl adss afaa afad afak afbs afca afcb afcc afcs afdb afdc afdl affa affc affs afka afla aflc afsa afsb afsc akaa akal akas akca akka aksa alaa alac alad alak alal alas alb- alba albc albs alca alcc alcs ald- alda aldl alds alfa alfs alk- alka alkb alkd all- alla alll alls alsa alsc asaa asab asac asad asaf asak asal asas asba asc- asca ascb ascc ascl asda asdf asdl asds asfa aska asks asla assa assc assd assk assl asss baaa baad baaf baak baal baas baba babb babs bac- baca bacc back bacs bada badb badd bads bafc baff bak- baka bakl baks bala balc bald balf balk ball bals basa basc basf bask bass bbad bbas bbbb bbbs bbdd bbfc bblb bbls bcaa bcas bcbc bcbs bcca bccc bccl bccs bcda bcds bcfc bcsa bcsc bcsl bcss bdbc bddc bdls bdsd bfas bfca bfcs bffl bffs blaa blab blac blad blak blas bldc blfc blkb blkd blls blss bsaa bsac bsas bsbd bscs bsdl bsfa bsfc bsff bsfs bslc bssc bssd c-cd caaa caab caac caaf caal caas caba cabf cabs cac- caca cacc cack cada cadc cadd cads cafa cafb cafc caff cafl cafs caka cala calc cald calf calk call cals casa casb casc casd cask casl cass cbac cbal cbbc cbbs cbca cbcc cbcl cbcs cbdb cbdc cbds cbfb cbfc cbka cbkl cblb cblc cbsa cbsc ccaa ccab ccac ccad ccaf ccas ccba ccbc ccca cccb cccc cccf cccl cccs ccdc ccdf ccds ccfa ccfc ccfd ccff ccfl ccla cclc ccls ccsa ccsd ccsf ccsl ccss cdaa cdac cdad cdba cdbf cdcs cdda cddb cddl cdfa cdfs cdls cdss cfaa cfab cfac cfbc cfbs cfca cfcb cfcf cfcl cfcs cfda cfds cffb cfls cfsa cfsl ckac ckbc ckck ckcl ckcs cklf cksa cksb cksl clab clad claf clas clcd cldc clsa clsc csaa csab csac csak csas csbf cscb cscc cscd cscf cscl cscs csda csdb csfc cska csks csla csld cssa cssd daab daad daal daas daba dabb dabs daca dacs dada dads dafa dafc daff dafs daka daks dala dalf dalk dall dals dasa dasb dasc dasd dask dasl dass dbas dbcc dbcs dbfc dbfs dbls dbsa dbss dcas dcbc dcca