a-a a-b a-c aaa aab aac aae aak aan aao aax ab- aba abb abc abe abk abn abo abx ac- aca acb acc ace ack acn aco acx aea aeb aec aee aek aen aeo aex aka akb akc ake akk akn ako an- ana anb anc ane ank ann ano anx aoa aob aoc aoe aok aon aoo aox ax- axa axe axk axn axo axx baa bab bac bae bak ban bao bax bba bbb bbc bbe bbk bbn bbo bbx bca bcb bcc bce bck bcn bco bcx be- bea beb bec bee bek ben beo bex bka bkb bkc bke bkk bkn bko bkx bna bnb bnc bne bnk bnn bno bnx boa bob boc boe bok bon boo box bxb bxn bxo bxx c-- caa cab cac cae cak can cao cax cba cbb cbc cbe cbk cbn cbo cbx cca ccb ccc cce cck ccn cco ccx ce- cea ceb cec cee cek cen ceo cex cka ckb ckc cko ckx cn- cna cnb cnc cne cnn cno cnx co- coa cob coc coe cok con coo cox cxc cxk cxo cxx eaa eab eac eae eak ean eao eax eba ebb ebc ebe ebk ebn ebo ebx ec- eca ecb ecc ece eck ecn eco ecx eea eeb eec eee eek een eeo eex eka ekb ekc eke eko en- ena enb enc ene enk enn eno eo- eoa eob eoc eoe eok eon eoo ex- exa exc exe exo exx ka- kaa kab kac kae kak kan kao kax kba kbb kbc kbe kbk kbn kbo kbx kca kcb kcc kce kck kcn kcx ke- kea keb kec kee kek ken keo kex kkb kkc kke kkk kkn kn- kna knc kne knk knn kno knx koa kob koc koe kok kon koo kxo naa nab nac nae nak nan nao nax nba nbb nbc nbe nbk nbn nbo nbx nca ncb ncc nce nck ncn nco ncx ne- nea neb nec nee nek nen neo nex nka nkc nke nkk nkn nko nna nnb nnc nne nnk nnn nno no- noa nob noc noe nok non noo nox nxc oaa oab oac oae oak oan oao oax ob- oba obb obc obe obk obn obo obx oc- oca ocb occ ock ocn oco ocx oea oeb oec oee oen oeo oex oka okb okc oke okk oko on- ona onb onc one onk onn ono onx oo- ooa oob ooc ook oon ooo oox ox- oxa oxb oxc oxn oxo oxx xaa xac xak xan xbc xbe xbx xcb xcx xee xen xex xkb xke xna xnc xnk xno xoa xoc xok xon xoo xox xxo xxx