<!DOCTYPE html>
<html>
<head>
    <title>Date Difference</title>
</head>
<body>
    <h1>Date Difference Calculator</h1>
    <form method="post" action="">
        <label for="birthdate">Select your birth date:</label>
        <select name="birthdate" id="birthdate">
            <?php
            // Generate the dropdown options for dates
            for ($day = 1; $day <= 31; $day++) {
                echo '<option value="' . $day . '">' . $day . '</option>';
            }
            ?>
        </select>
        <select name="birthmonth">
            <?php
            // Generate the dropdown options for months
            $months = [
                1 => 'January',
                2 => 'February',
                3 => 'March',
                4 => 'April',
                5 => 'May',
                6 => 'June',
                7 => 'July',
                8 => 'August',
                9 => 'September',
                10 => 'October',
                11 => 'November',
                12 => 'December'
            ];

            foreach ($months as $monthNumber => $monthName) {
                echo '<option value="' . $monthNumber . '">' . $monthName . '</option>';
            }
            ?>
        </select>
        <select name="birthyear">
            <?php
            // Generate the dropdown options for years
            $currentYear = date('Y');
            for ($year = $currentYear; $year >= ($currentYear - 100); $year--) {
                echo '<option value="' . $year . '">' . $year . '</option>';
            }
            ?>
        </select>
        <br><br>
        <input type="submit" value="Check Eligibility">
    </form>

    <?php
    if ($_SERVER['REQUEST_METHOD'] === 'POST') {
        // Retrieve the selected birth date
        $day = $_POST['birthdate'];
        $month = $_POST['birthmonth'];
        $year = $_POST['birthyear'];

        // Create the selected birth date and January 1, 2023 as DateTime objects
        $selectedDate = new DateTime($year . '-' . $month . '-' . $day);
        $january1_2023 = new DateTime('2023-01-01');

        // Calculate the difference in days
        $difference = $selectedDate->diff($january1_2023)->days;

        // Check eligibility and display the result
        if ($difference < 7300) {
            echo "<p>You are not eligible.</p>";
        } else {
            echo "<p>You are eligible.</p>";
        }
    }
    ?>
</body>
</html>

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