a-a a-b a-t aaa aab aak aan aao aat ab- aba abb abk abn abo abt aka akb akk akn ako an- ana anb ank ann ano ant aoa aob aok aon aoo aot at- ata atb atn ato att baa bab bak ban bao bat bba bbb bbk bbn bbo bbt bka bkb bkk bkn bko bkt bna bnb bnk bnn bno bnt boa bob bok bon boo bot bta btb btk btn bto btt k-t ka- kaa kab kak kan kao kat kba kbb kbk kbn kbo kkb kkk kkn kkt kn- kna knk knn kno knt koa kob kok kon koo kot kta ktb ktk ktn kto ktt naa nab nak nan nao nat nba nbb nbk nbn nbo nbt nka nkk nkn nko nkt nna nnb nnk nnn nno nnt no- noa nob nok non noo not nta ntb ntk ntn nto ntt oaa oab oak oan oao oat ob- oba obb obk obn obo obt oka okb okk oko on- ona onb onk onn ono ont oo- ooa oob ook oon ooo oot ot- ota otb otk otn oto ott taa tab tak tan tao tat tba tbb tbk tbn tbo tbt tka tkb tkk tko tkt tna tnb tnk tnn tno tnt to- toa tob tok ton too tot tta ttb ttk ttn tto ttt