-er a-a a-c aaa aac aae aaf aar ac- aca acc ace acf acr aea aec aee aef aer af- afa afc afe aff afr ar- ara arc are arf arr c-- caa cac cae caf car cca ccc cce ccf ccr ce- cea cec cee cef cer cfa cfc cfe cff cfr cra crc cre crf crr eaa eac eae eaf ear ec- eca ecc ece ecf ecr eea eec eee eef eer ef- efa efc efe eff efr era erc ere erf err faa fac fae faf far fca fcc fce fcf fcr fea fec fee fef fer ffa ffc ffe fff ffr fra frc fre frf frr ra- raa rac rae raf rar rca rcc rce rcf rcr re- rea rec ree ref rer rfa rfc rfe rff rfr rra rrc rrf rrr