a-a a-c a-t aaa aac aae aap aat aax ac- aca acc ace acp act acx aea aec aee aep aet aex ap- apa apc ape app apt apx at- ata atc ate atp att atx ax- axa axe axp axt axx c-- caa cac cae cap cat cax cca ccc cce ccp cct ccx ce- cea cec cee cep cet cex cpa cpc cpe cpp cpt cpx cta ctc cte ctp ctt ctx cxc cxp cxt cxx eaa eac eae eap eat eax ec- eca ecc ece ect ecx eea eec eee eep eet eex ep- epa epc epe epp ept epx eta etc ete etp ett etx ex- exa exc exe exp ext exx p-p paa pac pae pap pat pax pca pcc pce pcp pct pcx pea pec pee pep pet pex ppa ppc ppe ppp ppt ppx pt- pta ptc pte ptp ptt ptx pxc pxe pxt t-x taa tac tae tap tat tax tca tcc tce tcp tct tcx te- tea tec tee tep tet tex tpa tpc tpe tpp tpt tpx tta ttc tte ttp ttt ttx txe txt xaa xac xap xat xcp xcx xee xep xet xex xpa xpc xpe xpp xpt xtc xtp xtx xxp xxx