-er a-a a-c aaa aac aae aaf aag aak aan aar ac- aca acc ace acf acg ack acn acr aea aec aee aef aeg aek aen aer af- afa afc afe aff afg afk afn afr ag- aga agc age agf agg agk agn agr aka akc ake akg akk akn akr an- ana anc ane anf ang ank ann anr ar- ara arc are arf arg ark arn arr c-- caa cac cae caf cag cak can car cca ccc cce ccf ccg cck ccn ccr ce- cea cec cee cef ceg cek cen cer cfa cfc cfe cff cfg cfk cfn cfr cga cgc cge cgg cgn cgr cka ckc cn- cna cnc cne cnf cng cnn cnr cra crc cre crf crg crk crn crr eaa eac eae eaf eag eak ean ear ec- eca ecc ece ecf ecg eck ecn ecr eea eec eee eef eeg eek een eer ef- efa efc efe eff efg efr ega egc ege egf egg egn egr eka ekc eke ekf ekg ekr en- ena enc ene enf eng enk enn enr era erc ere erf erg erk ern err faa fac fae faf fag fak fan far fca fcc fce fcf fcg fck fcn fcr fea fec fee fef feg fek fen fer ffa ffc ffe fff ffg ffk ffn ffr fga fgc fge fgf fgg fgn fgr fka fkc fkf fkg fkk fna fnc fne fnf fng fnk fnn fnr fra frc fre frf frg frk frn frr gaa gac gae gaf gag gak gan gar gca gcc gce gcf gcg gck gcn gcr ge- gea gec gee gef geg gek gen ger gfa gfc gfe gff gfk gfr gga ggc ggg ggn ggr gka gkn gna gnc gne gnf gnn gnr gra grc gre grf grg grk grn grr ka- kaa kac kae kaf kag kak kan kar kca kcc kce kcg kck kcn kcr ke- kea kec kee kef keg kek ken ker kfa kfc kff kfg kga kgc kgf kkc kke kkk kkn kkr kn- kna knc kne knf kng knk knn knr kra krc krf krg krk krn krr naa nac nae naf nag nak nan nar nca ncc nce ncf ncg nck ncn ncr ne- nea nec nee nef neg nek nen ner nfa nfc nfe nff nfk nfn nfr nga ngc nge ngf ngg ngk ngn nka nkc nke nkf nkk nkn nkr nna nnc nne nnf nng nnk nnn nra nrc nre nrf nrg nrk nrn nrr ra- raa rac rae raf rag rak ran rar rca rcc rce rcf rcg rcn rcr re- rea rec ree ref reg rek ren rer rfa rfc rfe rff rfg rfk rfn rfr rga rgc rge rgf rgg rgk rgn rgr rkc rke rkf rkg rkk rna rnc rng rnn rnr rra rrc rrf rrg rrk rrn rrr