-er a-a a-c aaa aac aae aak aan aao aar ac- aca acc ace ack acn aco acr aea aec aee aek aen aeo aer aka akc ake akk akn ako akr an- ana anc ane ank ann ano anr aoa aoc aoe aok aon aoo aor ar- ara arc are ark arn aro arr c-- caa cac cae cak can cao car cca ccc cce cck ccn cco ccr ce- cea cec cee cek cen ceo cer cka ckc cko cn- cna cnc cne cnn cno cnr co- coa coc coe cok con coo cor cra crc cre crk crn cro crr eaa eac eae eak ean eao ear ec- eca ecc ece eck ecn eco ecr eea eec eee eek een eeo eer eka ekc eke eko ekr en- ena enc ene enk enn eno enr eo- eoa eoc eoe eok eon eoo eor era erc ere erk ern ero err ka- kaa kac kae kak kan kao kar kca kcc kce kck kcn kcr ke- kea kec kee kek ken keo ker kkc kke kkk kkn kkr kn- kna knc kne knk knn kno knr koa koc koe kok kon koo kor kra krc krk krn kro krr naa nac nae nak nan nao nar nca ncc nce nck ncn nco ncr ne- nea nec nee nek nen neo ner nka nkc nke nkk nkn nko nkr nna nnc nne nnk nnn nno no- noa noc noe nok non noo nor nra nrc nre nrk nrn nro nrr oaa oac oae oak oan oao oar oc- oca occ ock ocn oco ocr oea oec oee oen oeo oer oka okc oke okk oko okr on- ona onc one onk onn ono onr oo- ooa ooc ook oon ooo oor or- ora orc ore ork orn oro orr ra- raa rac rae rak ran rao rar rca rcc rce rcn rco rcr re- rea rec ree rek ren reo rer rkc rke rkk rko rna rnc rnn rno rnr roa roc roe rok ron roo ror rra rrc rrk rrn rrr