-er a-a a-c a-t aaa aac aae aao aar aat aax ac- aca acc ace aco acr act acx aea aec aee aeo aer aet aex aoa aoc aoe aoo aor aot aox ar- ara arc are aro arr art arx at- ata atc ate ato atr att atx ax- axa axe axo axr axt axx c-- caa cac cae cao car cat cax cca ccc cce cco ccr cct ccx ce- cea cec cee ceo cer cet cex co- coa coc coe coo cor cot cox cra crc cre cro crr crt crx cta ctc cte cto ctr ctt ctx cxc cxo cxr cxt cxx eaa eac eae eao ear eat eax ec- eca ecc ece eco ecr ect ecx eea eec eee eeo eer eet eex eo- eoa eoc eoe eoo eor eot era erc ere ero err ert eta etc ete eto etr ett etx ex- exa exc exe exo exr ext exx oaa oac oae oao oar oat oax oc- oca occ oco ocr oct ocx oea oec oee oeo oer oet oex oo- ooa ooc ooo oor oot oox or- ora orc ore oro orr ort orx ot- ota otc ote oto otr ott ox- oxa oxc oxo oxt oxx ra- raa rac rae rao rar rat rax rca rcc rce rco rcr rct rcx re- rea rec ree reo rer ret rex roa roc roe roo ror rot rox rra rrc rrr rrt rta rtc rte rto rtr rtt rtx rxr t-x taa tac tae tao tar tat tax tca tcc tce tco tcr tct tcx te- tea tec tee teo ter tet tex to- toa toc toe too tor tot tox tra trc tre tro trr trt trx tta ttc tte tto ttr ttt ttx txe txt xaa xac xar xat xcr xcx xee xer xet xex xoa xoc xoo xor xot xox xrc xrt xrx xtc xtr xtx xxo xxx