a-a a-b a-c a-t aaa aab aac aae aak aan aao aat ab- aba abb abc abe abk abn abo abt ac- aca acb acc ace ack acn aco act aea aeb aec aee aek aen aeo aet aka akb akc ake akk akn ako an- ana anb anc ane ank ann ano ant aoa aob aoc aoe aok aon aoo aot at- ata atb atc ate atn ato att baa bab bac bae bak ban bao bat bba bbb bbc bbe bbk bbn bbo bbt bca bcb bcc bce bck bcn bco bct be- bea beb bec bee bek ben beo bet bka bkb bkc bke bkk bkn bko bkt bna bnb bnc bne bnk bnn bno bnt boa bob boc boe bok bon boo bot bta btb btc bte btk btn bto btt c-- caa cab cac cae cak can cao cat cba cbb cbc cbe cbk cbn cbo cbt cca ccb ccc cce cck ccn cco cct ce- cea ceb cec cee cek cen ceo cet cka ckb ckc cko ckt cn- cna cnb cnc cne cnn cno cnt co- coa cob coc coe cok con coo cot cta ctb ctc cte ctk ctn cto ctt eaa eab eac eae eak ean eao eat eba ebb ebc ebe ebk ebn ebo ebt ec- eca ecb ecc ece eck ecn eco ect eea eeb eec eee eek een eeo eet eka ekb ekc eke eko ekt en- ena enb enc ene enk enn eno ent eo- eoa eob eoc eoe eok eon eoo eot eta etb etc ete etk etn eto ett k-t ka- kaa kab kac kae kak kan kao kat kba kbb kbc kbe kbk kbn kbo kca kcb kcc kce kck kcn kct ke- kea keb kec kee kek ken keo ket kkb kkc kke kkk kkn kkt kn- kna knc kne knk knn kno knt koa kob koc koe kok kon koo kot kta ktb ktc kte ktk ktn kto ktt naa nab nac nae nak nan nao nat nba nbb nbc nbe nbk nbn nbo nbt nca ncb ncc nce nck ncn nco nct ne- nea neb nec nee nek nen neo net nka nkc nke nkk nkn nko nkt nna nnb nnc nne nnk nnn nno nnt no- noa nob noc noe nok non noo not nta ntb ntc nte ntk ntn nto ntt oaa oab oac oae oak oan oao oat ob- oba obb obc obe obk obn obo obt oc- oca ocb occ ock ocn oco oct oea oeb oec oee oen oeo oet oka okb okc oke okk oko on- ona onb onc one onk onn ono ont oo- ooa oob ooc ook oon ooo oot ot- ota otb otc ote otk otn oto ott taa tab tac tae tak tan tao tat tba tbb tbc tbe tbk tbn tbo tbt tca tcb tcc tce tck tcn tco tct te- tea teb tec tee tek ten teo tet tka tkb tkc tke tkk tko tkt tna tnb tnc tne tnk tnn tno tnt to- toa tob toc toe tok ton too tot tta ttb ttc tte ttk ttn tto ttt