-al -ol a-a a-b a-c aaa aab aac aal aao aas ab- aba abb abc abl abo abs ac- aca acb acc acl aco acs al- ala alb alc all alo als aoa aob aoc aol aoo aos as- asa asb asc asl aso ass baa bab bac bal bao bas bba bbb bbc bbl bbo bbs bca bcb bcc bcl bco bcs bla blb blc bll blo bls boa bob boc bol boo bos bsa bsb bsc bsl bso bss c-- caa cab cac cal cao cas cba cbb cbc cbl cbo cbs cca ccb ccc ccl cco ccs cl- cla clb clc cll clo cls co- coa cob coc col coo cos csa csb csc csl cso css la- laa lab lac lal lao las lba lbb lbc lbl lbo lbs lca lcb lcc lcl lco lcs lla llb llc lll llo lls loa lob loc lol loo los lsa lsb lsc lsl lso lss oaa oab oac oal oao oas ob- oba obb obc obl obo obs oc- oca ocb occ ocl oco ocs ola olb olc oll olo ols oo- ooa oob ooc ool ooo oos os- osa osb osc osl oso oss saa sab sac sal sao sas sba sbb sbc sbl sbo sbs sca scb scc scl sco scs sla slb slc sll slo sls soa sob soc sol soo sos ss- ssa ssb ssc ssl sso sss