-er a-a a-c aaa aac aae aao aar ac- aca acc ace aco acr aea aec aee aeo aer aoa aoc aoe aoo aor ar- ara arc are aro arr c-- caa cac cae cao car cca ccc cce cco ccr ce- cea cec cee ceo cer co- coa coc coe coo cor cra crc cre cro crr eaa eac eae eao ear ec- eca ecc ece eco ecr eea eec eee eeo eer eo- eoa eoc eoe eoo eor era erc ere ero err oaa oac oae oao oar oc- oca occ oco ocr oea oec oee oeo oer oo- ooa ooc ooo oor or- ora orc ore oro orr ra- raa rac rae rao rar rca rcc rce rco rcr re- rea rec ree reo rer roa roc roe roo ror rra rrc rrr