a-a a-c aaa aac aad aak aao ac- aca acc acd ack aco ad- ada adc add adk ado aka akc akd akk ako aoa aoc aod aok aoo c-- caa cac cad cak cao cca ccc ccd cck cco cda cdc cdd cdk cdo cka ckc ckd cko co- coa coc cod cok coo daa dac dad dak dao dca dcc dcd dck dco dda ddc ddd ddk ddo dka dkc dkk dko doa doc dod dok doo ka- kaa kac kad kak kao kca kcc kcd kck kda kdc kdk kdo kkc kkk koa koc kod kok koo oaa oac oad oak oao oc- oca occ ocd ock oco oda odc odd odo oka okc okd okk oko oo- ooa ooc ood ook ooo