if(!open DAT, "ads.dat") {
    print "Error: cannot open data file!\n";
    exit 1;
} else {

    @imgdata=<DAT>;
    foreach $c (@imgdata) {
        ($id,$image,$url,$type)=split(/\|/,$c);

        if ($type=~/^(internal|partner)$/) {
            push (@imgs, $image);
        }
    }

    $img  = $imgs[int(rand($#imgs+1))];
    print "Location: $img\n\n";
}