<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Hello World 2</title>
    </head>
    <body>
        <ul>
            <?php
            if (isset($_GET["nb"])) {
                $nb = (int) $_GET["nb"];
                if ($nb >= 0 and $nb <= 100)
                for ($i = 0; $i < $nb; $i++) { ?>
                    <li>Hello World !</li>
                <?php }
            } else { ?>
                <strong>Invalid number !</strong>
            <?php } ?>
        </ul>
    </body>
</html>