a-a a-b a-t aaa aab aae aao aat aax ab- aba abb abe abo abt abx aea aeb aee aeo aet aex aoa aob aoe aoo aot aox at- ata atb ate ato att atx ax- axa axe axo axt axx baa bab bae bao bat bax bba bbb bbe bbo bbt bbx be- bea beb bee beo bet bex boa bob boe boo bot box bta btb bte bto btt btx bxb bxo bxx eaa eab eae eao eat eax eba ebb ebe ebo ebt ebx eea eeb eee eeo eet eex eo- eoa eob eoe eoo eot eta etb ete eto ett etx ex- exa exe exo ext exx oaa oab oae oao oat oax ob- oba obb obe obo obt obx oea oeb oee oeo oet oex oo- ooa oob ooo oot oox ot- ota otb ote oto ott ox- oxa oxb oxo oxt oxx t-x taa tab tae tao tat tax tba tbb tbe tbo tbt te- tea teb tee teo tet tex to- toa tob toe too tot tox tta ttb tte tto ttt ttx txe txt xaa xat xbe xbx xee xet xex xoa xoo xot xox xtx xxo xxx