a-a a-c a-t aaa aac aao aar aat aax ac- aca acc aco acr act acx aoa aoc aoo aor aot aox ar- ara arc aro arr art arx at- ata atc ato atr att atx ax- axa axo axr axt axx c-- caa cac cao car cat cax cca ccc cco ccr cct ccx co- coa coc coo cor cot cox cra crc cro crr crt crx cta ctc cto ctr ctt ctx cxc cxo cxr cxt cxx oaa oac oao oar oat oax oc- oca occ oco ocr oct ocx oo- ooa ooc ooo oor oot oox or- ora orc oro orr ort orx ot- ota otc oto otr ott ox- oxa oxc oxo oxt oxx ra- raa rac rao rar rat rax rca rcc rco rcr rct rcx roa roc roo ror rot rox rra rrc rrr rrt rta rtc rto rtr rtt rtx rxr t-x taa tac tao tar tat tax tca tcc tco tcr tct tcx to- toa toc too tor tot tox tra trc tro trr trt trx tta ttc tto ttr ttt ttx txt xaa xac xar xat xcr xcx xoa xoc xoo xor xot xox xrc xrt xrx xtc xtr xtx xxo xxx