a-a a-z aaa aao aas aax aay aaz aoa aoo aos aox as- asa aso ass asx asy asz ax- axa axo axs axx ay- aya ayo ays ayx ayz az- aza azo azs azx azy azz oaa oao oas oax oo- ooa ooo oos oox os- osa oso oss osx ox- oxa oxo oxx oxy oya oyo oys oza ozo ozs ozz saa sao sas sax say saz soa soo sos sox soy soz ss- ssa sso sss ssx ssz sxs sy- sya sys syx sza xaa xas xoa xoo xos xox xsa xss xxo xxx xxy xyy xyz yaa yao yas yax yay yaz yoo yos yox yoy ysa yso yss ysy ysz yxa yxy yys yyy yyz yzy zaa zao zas zax zay zaz zo- zoa zoo zos zox zsa zsz zxx zyx zzs zzx zzy zzz