a-a a-c aaa aac aaf aao aap aas ac- aca acc acf aco acp acs af- afa afc aff afo afp afs aoa aoc aof aoo aop aos ap- apa apc apf apo app aps as- asa asc asf aso asp ass c-- caa cac caf cao cap cas cca ccc ccf cco ccp ccs cfa cfc cff cfo cfp cfs co- coa coc cof coo cop cos cpa cpc cpf cpo cpp cps csa csc csf cso csp css faa fac faf fao fap fas fca fcc fcf fco fcp fcs ffa ffc fff ffo ffp ffs foa foc fof foo fop fos fpa fpc fpo fpp fps fsa fsc fsf fso fsp fss oaa oac oaf oao oap oas oc- oca occ ocf oco ocp ocs of- ofa ofc off ofo ofp ofs oo- ooa ooc oof ooo oop oos op- opa opc opf opo opp ops os- osa osc osf oso osp oss p-p paa pac paf pao pap pas pca pcc pcf pco pcp pcs pfa pfc pff pfo pfp pfs poa poc pof poo pop pos ppa ppc ppf ppo ppp pps ps- psa psc psf pso psp pss saa sac saf sao sap sas sca scc scf sco scp scs sfa sfc sff sfo sfp sfs soa soc sof soo sop sos spa spc spf spo spp sps ss- ssa ssc ssf sso ssp sss