-al a-a a-b a-c aaa aab aac aae aal aax ab- aba abb abc abe abl abx ac- aca acb acc ace acl acx aea aeb aec aee ael aex al- ala alb alc ale all alx ax- axa axe axl axx baa bab bac bae bal bax bba bbb bbc bbe bbl bbx bca bcb bcc bce bcl bcx be- bea beb bec bee bel bex bla blb blc ble bll blx bxb bxl bxx c-- caa cab cac cae cal cax cba cbb cbc cbe cbl cbx cca ccb ccc cce ccl ccx ce- cea ceb cec cee cel cex cl- cla clb clc cle cll clx cxc cxl cxx eaa eab eac eae eal eax eba ebb ebc ebe ebl ebx ec- eca ecb ecc ece ecl ecx eea eeb eec eee eel eex ela elb elc ele ell elx ex- exa exc exe exl exx la- laa lab lac lae lal lax lba lbb lbc lbe lbl lbx lca lcb lcc lce lcl lcx lea leb lec lee lel lex lla llb llc lle lll lxc lxx xaa xac xal xbc xbe xbl xbx xcb xcl xcx xee xel xex xla xlb xxl xxx