sub rotbynum
{
	my $t = shift(@_);
	my $r = shift(@_);
	if (!$r)
	{
		$r = 13;
	}
	$p = "";
	foreach $c (split(//, $t))
	{
		$o = ord($c);
		$o += $r;
		while ($o < 0)
		{
			$o += 256;
		}
		while ($o > 255)
		{
			$o -= 256;
		}
		$p = $p . chr($o);
	}
	return $p;
}

print rotbynum("I'm a little surprised that someone shows you the filename of a picture and you compare the filename to random body parts."), "\n\n";
print rotbynum("i like the number 8", 8), "\n\n";
print rotbynum("What's so special about the number 13 anyway?"), "\n\n";
print rotbynum("Bionic Commando", 8), "\n\n";
print rotbynum("i've got my own directory now! stay tuned!", 8), "\n\n";
print rotbynum("i like bmp files", 8), "\n\n";
print rotbynum("have you met wunder? she likes music. don't forget the zero", 8), "\n\n";
print rotbynum("i like bmp files", 7), "\n\n";
print rotbynum("i like bmp files", 8), "\n\n";
print rotbynum("i like bmp files", 9), "\n\n";
$v = reverse rotbynum("\@tugjit!332.8:!obiu!fspn!uvpcb!xpI!\@tmbtsfwfs!iujx!mbfe!uj!tfpe!uvc!epph!t(ubiU", -1);
print $v, "\n\n";