-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