a-a a-b aaa aab aad aae aak aan ab- aba abb abd abe abk abn ad- ada adb add ade adk adn aea aeb aed aee aek aen aka akb akd ake akk akn an- ana anb and ane ank ann baa bab bad bae bak ban bba bbb bbd bbe bbk bbn bda bdb bdd bde bdk be- bea beb bed bee bek ben bka bkb bke bkk bkn bna bnb bnd bne bnk bnn daa dab dad dae dak dan dba dbb dbd dbe dbk dbn dda ddb ddd dde ddk ddn de- dea deb ded dee dek den dka dkb dke dkk dna dnb dnd dne dnk dnn eaa eab ead eae eak ean eba ebb ebd ebe ebk ebn ed- eda edb edd ede edk edn eea eeb eed eee eek een eka ekb ekd eke en- ena enb end ene enk enn ka- kaa kab kad kae kak kan kba kbb kbd kbe kbk kbn kda kdb kde kdk ke- kea keb ked kee kek ken kkb kke kkk kkn kn- kna knd kne knk knn naa nab nad nae nak nan nba nbb nbd nbe nbk nbn nda ndb ndd nde ndk ndn ne- nea neb ned nee nek nen nka nke nkk nkn nna nnb nne nnk nnn