a-a a-c aaa aac aao aap aar aas ac- aca acc aco acp acr acs aoa aoc aoo aop aor aos ap- apa apc apo app apr aps ar- ara arc aro arp arr ars as- asa asc aso asp asr ass c-- caa cac cao cap car cas cca ccc cco ccp ccr ccs co- coa coc coo cop cor cos cpa cpc cpo cpp cpr cps cra crc cro crp crr crs csa csc cso csp csr css oaa oac oao oap oar oas oc- oca occ oco ocp ocr ocs oo- ooa ooc ooo oop oor oos op- opa opc opo opp opr ops or- ora orc oro orp orr ors os- osa osc oso osp osr oss p-p paa pac pao pap par pas pca pcc pco pcp pcr pcs poa poc poo pop por pos ppa ppc ppo ppp ppr pps pra prc pro prp prr prs ps- psa psc pso psp psr pss ra- raa rac rao rap rar ras rca rcc rco rcp rcr rcs roa roc roo rop ror ros rpa rpc rpo rpp rpr rps rra rrc rrp rrr rrs rsa rsc rso rsp rsr rss saa sac sao sap sar sas sca scc sco scp scr scs soa soc soo sop sor sos spa spc spo spp spr sps sr- sra src sro srp srr srs ss- ssa ssc sso ssp ssr sss