a-a a-b a-c a-t aaa aab aac aae aao aat aax ab- aba abb abc abe abo abt abx ac- aca acb acc ace aco act acx aea aeb aec aee aeo aet aex aoa aob aoc aoe aoo aot aox at- ata atb atc ate ato att atx ax- axa axe axo axt axx baa bab bac bae bao bat bax bba bbb bbc bbe bbo bbt bbx bca bcb bcc bce bco bct bcx be- bea beb bec bee beo bet bex boa bob boc boe boo bot box bta btb btc bte bto btt btx bxb bxo bxx c-- caa cab cac cae cao cat cax cba cbb cbc cbe cbo cbt cbx cca ccb ccc cce cco cct ccx ce- cea ceb cec cee ceo cet cex co- coa cob coc coe coo cot cox cta ctb ctc cte cto ctt ctx cxc cxo cxt cxx eaa eab eac eae eao eat eax eba ebb ebc ebe ebo ebt ebx ec- eca ecb ecc ece eco ect ecx eea eeb eec eee eeo eet eex eo- eoa eob eoc eoe eoo eot eta etb etc ete eto ett etx ex- exa exc exe exo ext exx oaa oab oac oae oao oat oax ob- oba obb obc obe obo obt obx oc- oca ocb occ oco oct ocx oea oeb oec oee oeo oet oex oo- ooa oob ooc ooo oot oox ot- ota otb otc ote oto ott ox- oxa oxb oxc oxo oxt oxx t-x taa tab tac tae tao tat tax tba tbb tbc tbe tbo tbt tca tcb tcc tce tco tct tcx te- tea teb tec tee teo tet tex to- toa tob toc toe too tot tox tta ttb ttc tte tto ttt ttx txe txt xaa xac xat xbc xbe xbx xcb xcx xee xet xex xoa xoc xoo xot xox xtc xtx xxo xxx