a-a a-c aaa aac aae aaf aao aas ac- aca acc ace acf aco acs aea aec aee aef aeo aes af- afa afc afe aff afo afs aoa aoc aoe aof aoo aos as- asa asc ase asf aso ass c-- caa cac cae caf cao cas cca ccc cce ccf cco ccs ce- cea cec cee cef ceo ces cfa cfc cfe cff cfo cfs co- coa coc coe cof coo cos csa csc cse csf cso css eaa eac eae eaf eao eas ec- eca ecc ece ecf eco ecs eea eec eee eef eeo ees ef- efa efc efe eff efo efs eo- eoa eoc eoe eof eoo eos es- esa esc ese esf eso ess faa fac fae faf fao fas fca fcc fce fcf fco fcs fea fec fee fef feo fes ffa ffc ffe fff ffo ffs foa foc foe fof foo fos fsa fsc fse fsf fso fss oaa oac oae oaf oao oas oc- oca occ ocf oco ocs oea oec oee oef oeo oes of- ofa ofc ofe off ofo ofs oo- ooa ooc oof ooo oos os- osa osc ose osf oso oss saa sac sae saf sao sas sca scc sce scf sco scs se- sea sec see sef seo ses sfa sfc sfe sff sfo sfs soa soc soe sof soo sos ss- ssa ssc sse ssf sso sss