-ic a-a a-b a-c a-i aaa aab aac aae aai aax ab- aba abb abc abe abi abx ac- aca acb acc ace aci acx aea aeb aec aee aei aex ai- aia aib aic aie aii aix ax- axa axe axi axx baa bab bac bae bai bax bba bbb bbc bbe bbi bbx bca bcb bcc bce bci bcx be- bea beb bec bee bei bex bi- bia bib bic bie bii bix bxb bxi bxx c-- caa cab cac cae cai cax cba cbb cbc cbe cbi cbx cca ccb ccc cce cci ccx ce- cea ceb cec cee cei cex ci- cia cib cic cie cii cix cxc cxi cxx eaa eab eac eae eai eax eba ebb ebc ebe ebi ebx ec- eca ecb ecc ece eci ecx eea eeb eec eee eex eia eib eic eie eii eix ex- exa exc exe exi exx ia- iaa iab iac iae iai iba ibb ibc ibe ibi ibx ica icb icc ice ici ie- iea iec iee iei iex iia iib iic iie iii iix ixc ixe ixi xaa xac xbc xbe xbx xcb xci xcx xee xex xia xic xie xii xix xxi xxx