a-a a-b a-t aaa aab aae aao aat ab- aba abb abe abo abt aea aeb aee aeo aet aoa aob aoe aoo aot at- ata atb ate ato att baa bab bae bao bat bba bbb bbe bbo bbt be- bea beb bee beo bet boa bob boe boo bot bta btb bte bto btt eaa eab eae eao eat eba ebb ebe ebo ebt eea eeb eee eeo eet eo- eoa eob eoe eoo eot eta etb ete eto ett oaa oab oae oao oat ob- oba obb obe obo obt oea oeb oee oeo oet oo- ooa oob ooo oot ot- ota otb ote oto ott taa tab tae tao tat tba tbb tbe tbo tbt te- tea teb tee teo tet to- toa tob toe too tot tta ttb tte tto ttt