I need some help

[BRADERY]

I wrote this script

 

<?php
$authKeysFile = "Authkeys.txt";
$keys = file($authKeysFile);
foreach($keys as $aKeys)
    {
    $Keys = explode(' ', $aKeys);
    $AccountInfo = array($Keys[0], $Keys[1]);
}
for($cwb=1; $cwb!=count($AccountInfo); $cwb++)
{
$Renew = file_get_contents("http://mob-dynamic-lb".rand(1,5).".mobsters0".rand(1,9).".com/mob/sign_in_secured?user_id=".$AccountInfo[0]."&sign_in=true&auth_key=".$AccountInfo[1]);
$NewAuth = explode("<auth_key>", $Renew);
$NewAuth = explode("<", $NewAuth[1]);
$NewKeys = $AccountInfo[0]." ".$NewAuth[0];
$z = fopen('NewAuthKeys.txt', 'a+');
fwrite($z, $NewKeys."\n");
fclose($z);
}
echo "Done updating keys...".sleep(10000);
?>

 

Now.. the content that is in the "AuthKeys.txt" is

 

537168014 10d668a39b59ffb63c7621279ff1246f12159dba
530830355 c91a3675f64353a56091449672b4af12a256336d

 

What the script does is loads the 9 Digit id and the auth key in the url and then writes to the file NewAuthKeys.txt.. the problem is that it is only writing the last id from the first text file after updating.. I could put 100 IDs and auth keys in the file and it would only update and write the last id to the text file.. what can I do to fix this