Meeting Dates 90/100 Time limit

<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Meeting Dates</title>
    <style>
        body {
            font-family: tahoma;
        }
    </style>
</head>
<body>
    <form action="" method="get">
        <input type="text" name="dateOne" value="31-12-2014"/>
        <input type="text" name="dateTwo" value="01-01-2014"/>
        <input type="submit" value="Submit"/>
    </form>
    <?php
        if (isset($_GET['dateOne']) && isset($_GET['dateTwo'])) {
            date_default_timezone_set('Europe/Sofia');
            $firstDate = strtotime($_GET['dateOne']);
            $secondDate = strtotime($_GET['dateTwo']);
            if ($firstDate > $secondDate) {
                $firstDate = $firstDate + $secondDate;
                $secondDate = $firstDate - $secondDate;
                $firstDate = $firstDate - $secondDate;
            }
            $thursDays = [];
            $AllDays = floor(($secondDate - $firstDate)/(60*60*24)) + 1;

            $currentDate = $firstDate;

            for ($i = 0; $i < $AllDays; $i++) {
                $dayOfWeek = date('N', $currentDate);
                if ($dayOfWeek == 4) {
                    array_push($thursDays , date("d-m-Y", $currentDate));
                }
                $currentDate = strtotime('+1 day', $currentDate);
            }

            if (count($thursDays) > 0) {
                echo '<ol>';
                foreach ($thursDays as $thursDay) {
                    echo '<li>' . $thursDay . '</li>';
                }
                echo '</ol>';
            }
            else {
                echo '<h2>No Thursdays</h2>';
            }
        }
    ?>
</body>
</html>