-er a-a a-c aaa aac aae aao aar aas aax ac- aca acc ace aco acr acs acx aea aec aee aeo aer aes aex aoa aoc aoe aoo aor aos aox ar- ara arc are aro arr ars arx as- asa asc ase aso asr ass asx ax- axa axe axo axr axs axx c-- caa cac cae cao car cas cax cca ccc cce cco ccr ccs ccx ce- cea cec cee ceo cer ces cex co- coa coc coe coo cor cos cox cra crc cre cro crr crs crx csa csc cse cso csr css csx cxc cxo cxr cxs cxx eaa eac eae eao ear eas eax ec- eca ecc ece eco ecr ecs ecx eea eec eee eeo eer ees eex eo- eoa eoc eoe eoo eor eos era erc ere ero err ers es- esa esc ese eso esr ess esx ex- exa exc exe exo exr exs exx oaa oac oae oao oar oas oax oc- oca occ oco ocr ocs ocx oea oec oee oeo oer oes oex oo- ooa ooc ooo oor oos oox or- ora orc ore oro orr ors orx os- osa osc ose oso osr oss osx ox- oxa oxc oxo oxx ra- raa rac rae rao rar ras rax rca rcc rce rco rcr rcs rcx re- rea rec ree reo rer res rex roa roc roe roo ror ros rox rra rrc rrr rrs rsa rsc rse rso rsr rss rsx rxr rxs saa sac sae sao sar sas sax sca scc sce sco scr scs scx se- sea sec see seo ser ses sex soa soc soe soo sor sos sox sr- sra src sre sro srr srs srx ss- ssa ssc sse sso ssr sss ssx sxc sxs xaa xac xar xas xcr xcx xee xer xes xex xoa xoc xoo xor xos xox xrc xrx xsa xsc xss xxo xxx