计算XML节点PHP

I'm faily new XML within PHP, and was hoping you clever people out there would be able to help me. Let's say I have an xml document which is full of users. Let me give you an example one of the users:

<user name="Cajs">
    <email>mail@cajs.co.uk</email>
    <server>Alpha</server>
    <referral>VQxwf3Wq4PS5WOqhljTDPUbA</referral>
    <limit>10</limit>
    <ips />
    <network id="EsperNet" created="1388534400"/>
    <network id="DALnet" created="1388534400"/>
    <network id="Freenode" created="1388534400"/>
    <network id="OnlineGamesNet" created="1388534400"/>
    <network id="PonyChat" created="1388534400"/>
    <network id="QuakeNet" created="1388534400"/>
    <network id="Rizon" created="1388534400"/>
    <network id="YourBNC" created="1388534400"/>
    <network id="AthemeNet" created="1406458342"/>
</user>

How would I count the total amount of networks of "ALL" users who have the server Alpha.

Thanks for all help!

* UPDATE * Please is it possible for when the removed= part is added to the tag it's ignored, example below:

You can solve this with help of XPath:

$xml = simplexml_load_string($xml);

$results = array();

foreach($xml->xpath('//user[server[.="Alpha"]]') as $user) {
    $results[] = array(
                       'name'          => (string)$user->attributes()->name,
                       'network_count' => $user->network->count()
                      );
}

var_dump($results);

$xml = simplexml_load_string($xmlString);
$countUsers = 0;
for( $i = 0; $i < $xml->count(); $i++ ) {
    if( $xml->user[$i]->server == 'Alpha' )
        $countUsers++;
}

var_dump($countUsers);

With DomDocument it would just be:

$xpath->query('//user[server[text()="Alpha"]]/network')->length;

I'm sure it's the same in simplexml but I never use that lib.

For the second part it's:

$xpath->query('//user[not(@removed) and server[text()="Alpha"]]/network')->length;