a-a a-c aaa aac aad aao aap ac- aca acc acd aco acp ad- ada adc add ado adp aoa aoc aod aoo aop ap- apa apc apd apo app c-- caa cac cad cao cap cca ccc ccd cco ccp cda cdc cdd cdo cdp co- coa coc cod coo cop cpa cpc cpd cpo cpp daa dac dad dao dap dca dcc dcd dco dcp dda ddc ddd ddo ddp doa doc dod doo dop dpa dpc dpd dpo dpp oaa oac oad oao oap oc- oca occ ocd oco ocp oda odc odd odo odp oo- ooa ooc ood ooo oop op- opa opc opd opo opp p-p paa pac pad pao pap pca pcc pcd pco pcp pda pdc pdd pdo pdp poa poc pod poo pop ppa ppc ppd ppo ppp