15.Sub-Lists

<ul>
<?php
if (isset($_GET['num1']) && isset($_GET['num2'])) {
    $num1 = intval($_GET['num1']);
    $num2 = intval($_GET['num2']);

    for ($i = 1; $i <= $num1; $i++) {
        echo "\t<li>List $i";

            echo "\t\t<ul>";
                for ($j = 1; $j <= $num2; $j++) {
                   echo "\t\t\t<li>Element $i.$j</li>\n";
                }
            echo "\t\t</ul>";
        echo "\t</li>";
    }

}
?>
</ul>