-al a-a a-b a-c aaa aab aac aad aal ab- aba abb abc abd abl ac- aca acb acc acd acl ad- ada adb adc add adl al- ala alb alc ald all baa bab bac bad bal bba bbb bbc bbd bbl bca bcb bcc bcd bcl bda bdb bdc bdd bdl bla blb blc bld bll c-- caa cab cac cad cal cba cbb cbc cbd cbl cca ccb ccc ccd ccl cda cdb cdc cdd cdl cl- cla clb clc cld cll daa dab dac dad dal dba dbb dbc dbd dbl dca dcb dcc dcd dcl dda ddb ddc ddd ddl dl- dla dlb dlc dld dll la- laa lab lac lad lal lba lbb lbc lbd lbl lca lcb lcc lcd lcl lda ldb ldc ldd ldl lla llb llc lld lll