File get content in cURL

<?php
if (isset($_POST['1']) && isset($_POST['2'])) {
    $1 .= htmlspecialchars($_POST['1']);
    $2 .= htmlspecialchars($_POST['2']);
    
    $get .= file_get_contents('lijst.txt');
    $get .= '?checker&1='.$1.'&2='.$2.'';
    $ch   = curl_init();
    curl_setopt($ch, CURLOPT_URL, $get);
    curl_setopt($ch, CURLOPT_TIMEOUT, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
    $data = curl_exec($ch);
    curl_close($ch);
    echo  $get;
} else {
?>
<form method="POST" action="">
<p>1</p>
<input type="text" name="1" placeholder="1">
<p>2</p>
<input type="text" name="2" placeholder="2">
<br>
<input type="submit" value="test">
</form>
<?php
}
?>