04.PositiveNum/NegativeNum

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>First Steps Into PHP</title>

</head>
<body>
<form>
    X: <input type="text" name="num1" />
    Y: <input type="text" name="num2" />
    Z: <input type="text" name="num3" />
    <input type="submit" />
</form>
<?php
    if (isset($_GET['num1']) && isset($_GET['num2']) && isset($_GET['num3'])) {
        $num1 = intval($_GET['num1']);
        $num2 = intval($_GET['num2']);
        $num3 = intval($_GET['num3']);
    }

    $numbers = [$num1, $num2, $num3];

    if (in_array(0, $numbers)) {
        echo "Positive";
        exit(0);
    }

    $numbers = array_filter($numbers, function($num) {
        return $num < 0;
    });

    $isPositive = count($numbers);
    if ($isPositive % 2 == 0) {
        echo "Positive";
    } else {
        echo "Negative";
    }
?>
</body>
</html>