while($line = <$in_fh>) {
 chomp $line;

	if ($line =~ /^(\d+)\.(\d+)\.(\d+)\.(\d+)/) {
		$a = $1;
		$b = $2;
		$c = $3;	
		$d = $4;
		$ip = "$a.$b.$c.$d";
		$classc = "$a.$b.$c";
	}

	next unless defined $ip;

	push @{ $ips{$classc} }, $ip;

}

foreach $classc (sort keys %ips) {
print $ips{$classc}[rand @{$ips{$classc}}] . "\n";
}