-al a-a a-b a-c aaa aab aac aak aal ab- aba abb abc abk abl ac- aca acb acc ack acl aka akb akc akk akl al- ala alb alc alk all baa bab bac bak bal bba bbb bbc bbk bbl bca bcb bcc bck bcl bka bkb bkc bkk bkl bla blb blc blk bll c-- caa cab cac cak cal cba cbb cbc cbk cbl cca ccb ccc cck ccl cka ckb ckc cl- cla clb clc clk cll ka- kaa kab kac kak kal kba kbb kbc kbk kbl kca kcb kcc kck kcl kkb kkc kkk kkl kl- kla klb klc la- laa lab lac lak lal lba lbb lbc lbk lbl lca lcb lcc lck lcl lka lkb lkl lla llb llc llk lll