-al -ol a-a a-b a-c aaa aab aac aal aao ab- aba abb abc abl abo ac- aca acb acc acl aco al- ala alb alc all alo aoa aob aoc aol aoo baa bab bac bal bao bba bbb bbc bbl bbo bca bcb bcc bcl bco bla blb blc bll blo boa bob boc bol boo c-- caa cab cac cal cao cba cbb cbc cbl cbo cca ccb ccc ccl cco cl- cla clb clc cll clo co- coa cob coc col coo la- laa lab lac lal lao lba lbb lbc lbl lbo lca lcb lcc lcl lco lla llb llc lll llo loa lob loc lol loo oaa oab oac oal oao ob- oba obb obc obl obo oc- oca ocb occ ocl oco ola olb olc oll olo oo- ooa oob ooc ool ooo