a-a a-b a-t aaa aab aae aaf aak aao aat ab- aba abb abe abf abk abo abt aea aeb aee aef aek aeo aet af- afa afb afe aff afk afo aft aka akb ake akk ako aoa aob aoe aof aok aoo aot at- ata atb ate atf ato att baa bab bae baf bak bao bat bba bbb bbe bbf bbk bbo bbt be- bea beb bee bef bek beo bet bfa bfb bfe bff bfo bft bka bkb bke bkf bkk bko bkt boa bob boe bof bok boo bot bta btb bte btf btk bto btt eaa eab eae eaf eak eao eat eba ebb ebe ebf ebk ebo ebt eea eeb eee eef eek eeo eet ef- efa efb efe eff efo eft eka ekb eke ekf eko ekt eo- eoa eob eoe eof eok eoo eot eta etb ete etf etk eto ett faa fab fae faf fak fao fat fba fbb fbe fbf fbk fbo fbt fea feb fee fef fek feo fet ffa ffe fff ffk ffo fft fka fkb fkf fkk fkt foa fob foe fof fok foo fot fta ftb fte ftf ftk fto ftt k-t ka- kaa kab kae kaf kak kao kat kba kbb kbe kbf kbk kbo ke- kea keb kee kef kek keo ket kfa kff kfo kkb kke kkk kkt koa kob koe kof kok koo kot kta ktb kte ktf ktk kto ktt oaa oab oae oaf oak oao oat ob- oba obb obe obf obk obo obt oea oeb oee oef oeo oet of- ofa ofb ofe off ofo oft oka okb oke okk oko oo- ooa oob oof ook ooo oot ot- ota otb ote otf otk oto ott taa tab tae taf tak tao tat tba tbb tbe tbf tbk tbo tbt te- tea teb tee tef tek teo tet tfa tfb tfe tff tfk tfo tft tka tkb tke tkk tko tkt to- toa tob toe tof tok too tot tta ttb tte ttf ttk tto ttt