a-a a-b a-c a-t aaa aab aac aae aaf aak aao aat ab- aba abb abc abe abf abk abo abt ac- aca acb acc ace acf ack aco act aea aeb aec aee aef aek aeo aet af- afa afb afc afe aff afk afo aft aka akb akc ake akk ako aoa aob aoc aoe aof aok aoo aot at- ata atb atc ate atf ato att baa bab bac bae baf bak bao bat bba bbb bbc bbe bbf bbk bbo bbt bca bcb bcc bce bcf bck bco bct be- bea beb bec bee bef bek beo bet bfa bfb bfc bfe bff bfo bft bka bkb bkc bke bkf bkk bko bkt boa bob boc boe bof bok boo bot bta btb btc bte btf btk bto btt c-- caa cab cac cae caf cak cao cat cba cbb cbc cbe cbf cbk cbo cbt cca ccb ccc cce ccf cck cco cct ce- cea ceb cec cee cef cek ceo cet cfa cfb cfc cfe cff cfk cfo cft cka ckb ckc cko ckt co- coa cob coc coe cof cok coo cot cta ctb ctc cte ctf ctk cto ctt eaa eab eac eae eaf eak eao eat eba ebb ebc ebe ebf ebk ebo ebt ec- eca ecb ecc ece ecf eck eco ect eea eeb eec eee eef eek eeo eet ef- efa efb efc efe eff efo eft eka ekb ekc eke ekf eko ekt eo- eoa eob eoc eoe eof eok eoo eot eta etb etc ete etf etk eto ett faa fab fac fae faf fak fao fat fba fbb fbc fbe fbf fbk fbo fbt fca fcb fcc fce fcf fck fco fct fea feb fec fee fef fek feo fet ffa ffc ffe fff ffk ffo fft fka fkb fkc fkf fkk fkt foa fob foc foe fof fok foo fot fta ftb ftc fte ftf ftk fto ftt k-t ka- kaa kab kac kae kaf kak kao kat kba kbb kbc kbe kbf kbk kbo kca kcb kcc kce kck kct ke- kea keb kec kee kef kek keo ket kfa kfc kff kfo kkb kkc kke kkk kkt koa kob koc koe kof kok koo kot kta ktb ktc kte ktf ktk kto ktt oaa oab oac oae oaf oak oao oat ob- oba obb obc obe obf obk obo obt oc- oca ocb occ ocf ock oco oct oea oeb oec oee oef oeo oet of- ofa ofb ofc ofe off ofo oft oka okb okc oke okk oko oo- ooa oob ooc oof ook ooo oot ot- ota otb otc ote otf otk oto ott taa tab tac tae taf tak tao tat tba tbb tbc tbe tbf tbk tbo tbt tca tcb tcc tce tcf tck tco tct te- tea teb tec tee tef tek teo tet tfa tfb tfc tfe tff tfk tfo tft tka tkb tkc tke tkk tko tkt to- toa tob toc toe tof tok too tot tta ttb ttc tte ttf ttk tto ttt