Clown - Negative - Positive Numbers

<!DOCTYPE html>
<html lang="hu">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
<?php
@$num=0;

 if(isset($_POST['gomb'])) {
    writeout();

@$num=$_POST['szam'];

}

function writeout(){
$num = $_POST['szam'];
$pre="";

if ($num!=0)
{

$pre =  ($num>=0) ? "pozitív" :  "negativ";

}
else
{$pre ="semleges";}


 print_r($pre);

}

?>

<form name="form" method="POST" action="<?php echo $_SERVER['PHP_SELF']; ?>">
<input type="number" value="<?php print @$num; ?>" name="szam" id="szam">
<button type="submit" name="gomb" id="gomb" >Kattints ide</button>


</form>


</body>
</html>