Question 907466
z*** 
*z**
**z*
***z

Can the * be another z? If so there are 26 possible choices.
If not then there are 25 possible choices. 
{{{N=1*26*26*26+26*1*26*26+26*26*1*26+26*26*26*1}}}
{{{N=4*26*26*26}}} 
or
{{{N=1*25*25*25+25*1*25*25+25*25*1*25+25*25*25*1}}}
{{{N=4*25*25*25}}}