a-a a-c aaa aac aao aap aas ac- aca acc aco acp acs aoa aoc aoo aop aos ap- apa apc apo app aps as- asa asc aso asp ass c-- caa cac cao cap cas cca ccc cco ccp ccs co- coa coc coo cop cos cpa cpc cpo cpp cps csa csc cso csp css oaa oac oao oap oas oc- oca occ oco ocp ocs oo- ooa ooc ooo oop oos op- opa opc opo opp ops os- osa osc oso osp oss p-p paa pac pao pap pas pca pcc pco pcp pcs poa poc poo pop pos ppa ppc ppo ppp pps ps- psa psc pso psp pss saa sac sao sap sas sca scc sco scp scs soa soc soo sop sos spa spc spo spp sps ss- ssa ssc sso ssp sss