note eyepopslikeamosquito <P> As you might expect, this has been golfed a few times before. For example: <ul> <li> [id://406374] (Perl Monks) <li> <a href="http://wikipedia.qwika.com/wiki/Perl#Example_Program">Qwika Perl wikipedia example program</a> <li> <a href="http://golf.shinh.org/p.rb?rot13">shinh's golf site rot13 game</a> </ul> The Qwika Perl wikipedia example program (which matches Anony's response above) is: <CODE> perl -pe 'tr/A-Za-z/N-ZA-Mn-za-m/' < input_file > output_file </CODE> while the shortest Perl solution at shinh's golf site is: <CODE> #!perl -p y/N-ZA-z/A-za-m/ </CODE> </P> 887321 887321