#!/usr/bin/perl
use strict;
use warnings;

my ($final, $rot);

$_ = shift;

open (INFILE, $_) || die "Can't open $_: $!";

while (<INFILE>) {
	foreach (split //) {
		if (/[a-m]/i) {
			$rot = 13;
		} elsif (/[n-z]/i) {
			$rot = -13;
		} else {
			$rot = 0;
		}
		$final .= chr(ord() + $rot);
	}
}
close(INFILE);

print $final;