-er a-a a-c aaa aac aae aar aas ac- aca acc ace acr acs aea aec aee aer aes ar- ara arc are arr ars as- asa asc ase asr ass c-- caa cac cae car cas cca ccc cce ccr ccs ce- cea cec cee cer ces cra crc cre crr crs csa csc cse csr css eaa eac eae ear eas ec- eca ecc ece ecr ecs eea eec eee eer ees era erc ere err ers es- esa esc ese esr ess ra- raa rac rae rar ras rca rcc rce rcr rcs re- rea rec ree rer res rra rrc rrr rrs rsa rsc rse rsr rss saa sac sae sar sas sca scc sce scr scs se- sea sec see ser ses sr- sra src sre srr srs ss- ssa ssc sse ssr sss