-al -ol a-a a-b a-c aaa aab aac aak aal aao aas ab- aba abb abc abk abl abo abs ac- aca acb acc ack acl aco acs aka akb akc akk akl ako aks al- ala alb alc alk all alo als aoa aob aoc aok aol aoo aos as- asa asb asc ask asl aso ass baa bab bac bak bal bao bas bba bbb bbc bbk bbl bbo bbs bca bcb bcc bck bcl bco bcs bka bkb bkc bkk bkl bko bks bla blb blc blk bll blo bls boa bob boc bok bol boo bos bsa bsb bsc bsk bsl bso bss c-- caa cab cac cak cal cao cas cba cbb cbc cbk cbl cbo cbs cca ccb ccc cck ccl cco ccs cka ckb ckc cko cks cl- cla clb clc clk cll clo cls co- coa cob coc cok col coo cos csa csb csc csk csl cso css ka- kaa kab kac kak kal kao kas kba kbb kbc kbk kbl kbo kbs kca kcb kcc kck kcl kcs kkb kkc kkk kkl kks kl- kla klb klc klo kls koa kob koc kok kol koo kos ksa ksb ksc ksk ksl kso kss la- laa lab lac lak lal lao las lba lbb lbc lbk lbl lbo lbs lca lcb lcc lck lcl lco lcs lka lkb lkl lks lla llb llc llk lll llo lls loa lob loc lok lol loo los lsa lsb lsc lsk lsl lso lss oaa oab oac oak oal oao oas ob- oba obb obc obk obl obo obs oc- oca ocb occ ock ocl oco ocs oka okb okc okk okl oko oks ola olb olc olk oll olo ols oo- ooa oob ooc ook ool ooo oos os- osa osb osc osk osl oso oss saa sab sac sak sal sao sas sba sbb sbc sbk sbl sbo sbs sca scb scc sck scl sco scs sk- ska skb skc skk skl sko sks sla slb slc slk sll slo sls soa sob soc sok sol soo sos ss- ssa ssb ssc ssk ssl sso sss