a-a a-i aaa aaf aai aax aay af- afa aff afi afx afy ai- aia aif aii aix aiy ax- axa axi axx ay- aya ayf ayi ayx faa faf fai fax fay ffa fff ffi ffx ffy fia fif fii fix fxi fxx fy- fya fyi i-f ia- iaa iaf iai ifa iff ifi ifx ify iia iif iii iix ixi ixy iya iyy xaa xaf xfa xfx xia xii xix xxi xxx xxy xyy yaa yaf yai yax yay yfa yff yif yii yxa yxy yyf yyy