Most Frequent Tag

<!--Write a PHP script MostFrequentTag.php which generates an HTML input text field and a submit button.
In the text field the user must enter different tags, separated by a comma and a space (", ").
When the information is submitted, the script should generate a list of the tags, sorted by frequency.
Then you must print: "Most Frequent Tag is: [most frequent tag]". Semantic HTML is required.
Styling is not required.-->

<!DOCTYPE html>
<html>
<head lang="en">
    <meta content="text/html" charset="UTF-8">
    <title>Most Frequent Tag</title>
</head>
<body>
<form action="#" method="get">
    <p><label for="tags">Enter Tags:</label></p>
    <input type="text" name="tags" id="tags" required/>
    <input type="submit" value="Submit"/>
</form>
<?php
if ($_GET && $_GET['tags']) {
    $tags = explode(', ', trim($_GET['tags']));
    $tags = array_count_values($tags);
    arsort($tags);

    foreach ($tags as $key => $value) {
        echo '<p>' . htmlspecialchars($key) . " : $value times</p>\n";
    }

    $keys = array_keys($tags);
    echo '<p>Most Frequent Tag is: ' . htmlspecialchars($keys[0]) . "</p>\n";
}
?>
</body>
</html>