What's the simplest way of adding one to a binary string in Perl?

Argument "nr&" isn't numeric in addition (+) at test.pm line 95.

pack("N", unpack("N", $ip&$netmask) + 1)

use Socket;

$ip = pack("C4", 192,168,250,66); # why not inet_aton("192.168.250.66")
$netmask = pack("C4", 255,255,255,0);

$ipi = unpack("N", $ip);
$netmaski = unpack("N", $netmask);

$ip1 = pack("N", ($ipi&$netmaski)+1);
print inet_ntoa($ip1), "n";

192.168.250.1