-al -ol a-a a-b a-c a-t aaa aab aac aal aao aat ab- aba abb abc abl abo abt ac- aca acb acc acl aco act al- ala alb alc all alo alt aoa aob aoc aol aoo aot at- ata atb atc atl ato att baa bab bac bal bao bat bba bbb bbc bbl bbo bbt bca bcb bcc bcl bco bct bla blb blc bll blo blt boa bob boc bol boo bot bta btb btc btl bto btt c-- caa cab cac cal cao cat cba cbb cbc cbl cbo cbt cca ccb ccc ccl cco cct cl- cla clb clc cll clo clt co- coa cob coc col coo cot cta ctb ctc ctl cto ctt la- laa lab lac lal lao lat lba lbb lbc lbl lbo lbt lca lcb lcc lcl lco lct lla llb llc lll llo llt loa lob loc lol loo lot lta ltb ltc ltl lto ltt oaa oab oac oal oao oat ob- oba obb obc obl obo obt oc- oca ocb occ ocl oco oct ola olb olc oll olo olt oo- ooa oob ooc ool ooo oot ot- ota otb otc otl oto ott taa tab tac tal tao tat tba tbb tbc tbl tbo tbt tca tcb tcc tcl tco tct tla tlc tll tlo tlt to- toa tob toc tol too tot tta ttb ttc ttl tto ttt