-er a-a a-c aaa aac aae aak aao aar aav ac- aca acc ace ack aco acr acv aea aec aee aek aeo aer aev aka akc ake akk ako akr akv aoa aoc aoe aok aoo aor aov ar- ara arc are ark aro arr arv av- ava avc ave avk avo avr c-- caa cac cae cak cao car cav cca ccc cce cck cco ccr ccv ce- cea cec cee cek ceo cer cev cka ckc cko co- coa coc coe cok coo cor cov cra crc cre crk cro crr crv cva cvc cve cvk cvo cvr cvv eaa eac eae eak eao ear eav ec- eca ecc ece eck eco ecr ecv eea eec eee eek eeo eer eev eka ekc eke eko ekr ekv eo- eoa eoc eoe eok eoo eor era erc ere erk ero err erv eva evc eve evo evr evv ka- kaa kac kae kak kao kar kav kca kcc kce kck kcr ke- kea kec kee kek keo ker kev kkc kke kkk kkr kkv koa koc koe kok koo kor kra krc krk kro krr krv kva kvk kvo kvr kvv oaa oac oae oak oao oar oav oc- oca occ ock oco ocr ocv oea oec oee oeo oer oka okc oke okk oko okr oo- ooa ooc ook ooo oor oov or- ora orc ore ork oro orr orv ov- ova ovc ove ovo ovv ra- raa rac rae rak rao rar rav rca rcc rce rco rcr rcv re- rea rec ree rek reo rer rev rkc rke rkk rko rkv roa roc roe rok roo ror rov rra rrc rrk rrr rva rvc rve rvo rvr rvv v-a v-e vaa vac vae vak vao var vav vca vcc vce vco vcr vea vec vee vek veo ver vka voa voc voe vok voo vor vov vra vrc vre vrk vrr vva vvc vvo vvr vvv