-er a-a a-c aaa aac aae aaf aag aar ac- aca acc ace acf acg acr aea aec aee aef aeg aer af- afa afc afe aff afg afr ag- aga agc age agf agg agr ar- ara arc are arf arg arr c-- caa cac cae caf cag car cca ccc cce ccf ccg ccr ce- cea cec cee cef ceg cer cfa cfc cfe cff cfg cfr cga cgc cge cgg cgr cra crc cre crf crg crr eaa eac eae eaf eag ear ec- eca ecc ece ecf ecg ecr eea eec eee eef eeg eer ef- efa efc efe eff efg efr ega egc ege egf egg egr era erc ere erf erg err faa fac fae faf fag far fca fcc fce fcf fcg fcr fea fec fee fef feg fer ffa ffc ffe fff ffg ffr fga fgc fge fgf fgg fgr fra frc fre frf frg frr gaa gac gae gaf gag gar gca gcc gce gcf gcg gcr ge- gea gec gee gef geg ger gfa gfc gfe gff gfr gga ggc ggg ggr gra grc gre grf grg grr ra- raa rac rae raf rag rar rca rcc rce rcf rcg rcr re- rea rec ree ref reg rer rfa rfc rfe rff rfg rfr rga rgc rge rgf rgg rgr rra rrc rrf rrg rrr