a-a a-c aaa aac aao aap aar ac- aca acc aco acp acr aoa aoc aoo aop aor ap- apa apc apo app apr ar- ara arc aro arp arr c-- caa cac cao cap car cca ccc cco ccp ccr co- coa coc coo cop cor cpa cpc cpo cpp cpr cra crc cro crp crr oaa oac oao oap oar oc- oca occ oco ocp ocr oo- ooa ooc ooo oop oor op- opa opc opo opp opr or- ora orc oro orp orr p-p paa pac pao pap par pca pcc pco pcp pcr poa poc poo pop por ppa ppc ppo ppp ppr pra prc pro prp prr ra- raa rac rao rap rar rca rcc rco rcp rcr roa roc roo rop ror rpa rpc rpo rpp rpr rra rrc rrp rrr