a-a a-b a-c aaa aab aac aae aan aas aax ab- aba abb abc abe abn abs abx ac- aca acb acc ace acn acs acx aea aeb aec aee aen aes aex an- ana anb anc ane ann ans anx as- asa asb asc ase asn ass asx ax- axa axe axn axs axx baa bab bac bae ban bas bax bba bbb bbc bbe bbn bbs bbx bca bcb bcc bce bcn bcs bcx be- bea beb bec bee ben bes bex bna bnb bnc bne bnn bns bnx bsa bsb bsc bse bsn bss bsx bxb bxn bxx c-- caa cab cac cae can cas cax cba cbb cbc cbe cbn cbs cbx cca ccb ccc cce ccn ccs ccx ce- cea ceb cec cee cen ces cex cn- cna cnb cnc cne cnn cns cnx csa csb csc cse csn css csx cxc cxs cxx eaa eab eac eae ean eas eax eba ebb ebc ebe ebn ebs ebx ec- eca ecb ecc ece ecn ecs ecx eea eeb eec eee een ees eex en- ena enb enc ene enn ens es- esa esb esc ese esn ess esx ex- exa exc exe exs exx naa nab nac nae nan nas nax nba nbb nbc nbe nbn nbs nbx nca ncb ncc nce ncn ncs ncx ne- nea neb nec nee nen nes nex nna nnb nnc nne nnn nns nsa nsb nsc nse nsn nss nsx nxc saa sab sac sae san sas sax sba sbb sbc sbe sbn sbs sbx sca scb scc sce scn scs scx se- sea seb sec see sen ses sex sna snb snc sne snn sns ss- ssa ssb ssc sse ssn sss ssx sxc sxn sxs xaa xac xan xas xbc xbe xbx xcb xcx xee xen xes xex xna xnc xns xsa xsb xsc xss xxx