-al a-a a-b a-c aaa aab aac aae aaf aak aal aan ab- aba abb abc abe abf abk abl abn ac- aca acb acc ace acf ack acl acn aea aeb aec aee aef aek ael aen af- afa afb afc afe aff afk afl afn aka akb akc ake akk akl akn al- ala alb alc ale alf alk all aln an- ana anb anc ane anf ank anl ann baa bab bac bae baf bak bal ban bba bbb bbc bbe bbf bbk bbl bbn bca bcb bcc bce bcf bck bcl bcn be- bea beb bec bee bef bek bel ben bfa bfb bfc bfe bff bfl bfn bka bkb bkc bke bkf bkk bkl bkn bla blb blc ble blf blk bll bln bna bnb bnc bne bnf bnk bnl bnn c-- caa cab cac cae caf cak cal can cba cbb cbc cbe cbf cbk cbl cbn cca ccb ccc cce ccf cck ccl ccn ce- cea ceb cec cee cef cek cel cen cfa cfb cfc cfe cff cfk cfl cfn cka ckb ckc cl- cla clb clc cle clf clk cll cln cn- cna cnb cnc cne cnf cnl cnn eaa eab eac eae eaf eak eal ean eba ebb ebc ebe ebf ebk ebl ebn ec- eca ecb ecc ece ecf eck ecl ecn eea eeb eec eee eef eek eel een ef- efa efb efc efe eff efl eka ekb ekc eke ekf ekl ela elb elc ele elf elk ell eln en- ena enb enc ene enf enk enl enn faa fab fac fae faf fak fal fan fba fbb fbc fbe fbf fbk fbl fbn fca fcb fcc fce fcf fck fcl fcn fea feb fec fee fef fek fel fen ffa ffc ffe fff ffk ffl ffn fka fkb fkc fkf fkk fkl fla flb flc fle flf fll fln fna fnb fnc fne fnf fnk fnl fnn ka- kaa kab kac kae kaf kak kal kan kba kbb kbc kbe kbf kbk kbl kbn kca kcb kcc kce kck kcl kcn ke- kea keb kec kee kef kek kel ken kfa kfc kff kkb kkc kke kkk kkl kkn kl- kla klb klc klf kn- kna knc kne knf knk knl knn la- laa lab lac lae laf lak lal lan lba lbb lbc lbe lbf lbk lbl lca lcb lcc lce lcf lck lcl lcn lea leb lec lee lef lek lel len lfa lfb lfc lfe lff lfk lfl lfn lka lkb lkl lla llb llc lle llf llk lll lln lna lnb lnc lne lnk lnl lnn naa nab nac nae naf nak nal nan nba nbb nbc nbe nbf nbk nbl nbn nca ncb ncc nce ncf nck ncl ncn ne- nea neb nec nee nef nek nel nen nfa nfb nfc nfe nff nfk nfl nfn nka nkc nke nkf nkk nkn nla nlb nlc nle nlf nlk nll nln nna nnb nnc nne nnf nnk nnl nnn