a-a a-b a-t aaa aab aae aaf aak aat ab- aba abb abe abf abk abt aea aeb aee aef aek aet af- afa afb afe aff afk aft aka akb ake akk at- ata atb ate atf att baa bab bae baf bak bat bba bbb bbe bbf bbk bbt be- bea beb bee bef bek bet bfa bfb bfe bff bft bka bkb bke bkf bkk bkt bta btb bte btf btk btt eaa eab eae eaf eak eat eba ebb ebe ebf ebk ebt eea eeb eee eef eek eet ef- efa efb efe eff eft eka ekb eke ekf ekt eta etb ete etf etk ett faa fab fae faf fak fat fba fbb fbe fbf fbk fbt fea feb fee fef fek fet ffa ffe fff ffk fft fka fkb fkf fkk fkt fta ftb fte ftf ftk ftt k-t ka- kaa kab kae kaf kak kat kba kbb kbe kbf kbk ke- kea keb kee kef kek ket kfa kff kkb kke kkk kkt kta ktb kte ktf ktk ktt taa tab tae taf tak tat tba tbb tbe tbf tbk tbt te- tea teb tee tef tek tet tfa tfb tfe tff tfk tft tka tkb tke tkk tkt tta ttb tte ttf ttk ttt