a-a a-b a-c aaa aab aac aad aae aak aan ab- aba abb abc abd abe abk abn ac- aca acb acc acd ace ack acn ad- ada adb adc add ade adk adn aea aeb aec aed aee aek aen aka akb akc akd ake akk akn an- ana anb anc and ane ank ann baa bab bac bad bae bak ban bba bbb bbc bbd bbe bbk bbn bca bcb bcc bcd bce bck bcn bda bdb bdc bdd bde bdk be- bea beb bec bed bee bek ben bka bkb bkc bke bkk bkn bna bnb bnc bnd bne bnk bnn c-- caa cab cac cad cae cak can cba cbb cbc cbd cbe cbk cbn cca ccb ccc ccd cce cck ccn cda cdb cdc cdd cde cdk cdn ce- cea ceb cec ced cee cek cen cka ckb ckc ckd cn- cna cnb cnc cnd cne cnn daa dab dac dad dae dak dan dba dbb dbc dbd dbe dbk dbn dca dcb dcc dcd dce dck dcn dda ddb ddc ddd dde ddk ddn de- dea deb dec ded dee dek den dka dkb dkc dke dkk dna dnb dnc dnd dne dnk dnn eaa eab eac ead eae eak ean eba ebb ebc ebd ebe ebk ebn ec- eca ecb ecc ecd ece eck ecn ed- eda edb edc edd ede edk edn eea eeb eec eed eee eek een eka ekb ekc ekd eke en- ena enb enc end ene enk enn ka- kaa kab kac kad kae kak kan kba kbb kbc kbd kbe kbk kbn kca kcb kcc kcd kce kck kcn kda kdb kdc kde kdk ke- kea keb kec ked kee kek ken kkb kkc kke kkk kkn kn- kna knc knd kne knk knn naa nab nac nad nae nak nan nba nbb nbc nbd nbe nbk nbn nca ncb ncc ncd nce nck ncn nda ndb ndc ndd nde ndk ndn ne- nea neb nec ned nee nek nen nka nkc nke nkk nkn nna nnb nnc nne nnk nnn