-al -ol a-a a-b a-c aaa aab aac aak aal aao aar aas ab- aba abb abc abk abl abo abr abs ac- aca acb acc ack acl aco acr acs aka akb akc akk akl ako akr aks al- ala alb alc alk all alo alr als aoa aob aoc aok aol aoo aor aos ar- ara arb arc ark arl aro arr ars as- asa asb asc ask asl aso asr ass baa bab bac bak bal bao bar bas bba bbb bbc bbk bbl bbo bbr bbs bca bcb bcc bck bcl bco bcr bcs bka bkb bkc bkk bkl bko bkr bks bla blb blc blk bll blo blr bls boa bob boc bok bol boo bor bos bra brb brk brl bro brr brs bsa bsb bsc bsk bsl bso bsr bss c-- caa cab cac cak cal cao car cas cba cbb cbc cbk cbl cbo cbr cbs cca ccb ccc cck ccl cco ccr ccs cka ckb ckc cko cks cl- cla clb clc clk cll clo clr cls co- coa cob coc cok col coo cor cos cra crb crc crk crl cro crr crs csa csb csc csk csl cso csr css ka- kaa kab kac kak kal kao kar kas kba kbb kbc kbk kbl kbo kbr kbs kca kcb kcc kck kcl kcr kcs kkb kkc kkk kkl kkr kks kl- kla klb klc klo klr kls koa kob koc kok kol koo kor kos kra krc krk krl kro krr krs ksa ksb ksc ksk ksl kso ksr kss la- laa lab lac lak lal lao lar las lba lbb lbc lbk lbl lbo lbr lbs lca lcb lcc lck lcl lco lcr lcs lka lkb lkl lkr lks lla llb llc llk lll llo llr lls loa lob loc lok lol loo lor los lra lrb lrc lrk lro lrr lrs lsa lsb lsc lsk lsl lso lsr lss oaa oab oac oak oal oao oar oas ob- oba obb obc obk obl obo obr obs oc- oca ocb occ ock ocl oco ocr ocs oka okb okc okk okl oko okr oks ola olb olc olk oll olo ols oo- ooa oob ooc ook ool ooo oor oos or- ora orb orc ork orl oro orr ors os- osa osb osc osk osl oso osr oss ra- raa rab rac rak ral rao rar ras rba rbb rbc rbk rbl rbo rbr rbs rca rcb rcc rcl rco rcr rcs rkb rkc rkk rko rks rla rlc rll rlo rlr rls roa rob roc rok rol roo ror ros rra rrb rrc rrk rrl rrr rrs rsa rsb rsc rsk rsl rso rsr rss saa sab sac sak sal sao sar sas sba sbb sbc sbk sbl sbo sbr sbs sca scb scc sck scl sco scr scs sk- ska skb skc skk skl sko skr sks sla slb slc slk sll slo slr sls soa sob soc sok sol soo sor sos sr- sra srb src srk srl sro srr srs ss- ssa ssb ssc ssk ssl sso ssr sss