Is it possible to get $flag?

Question

PHP

There is a page source:

<?php
  include('flag.php');
  if(strcmp($_POST['password'], $password) == 0) {
    echo $flag;
  }
?>

<form method="post">
  <input type="password" name="password" placeholder="Enter password">
  <input type="submit" value="Enter">
</form>

How can I get $flag? There is access to this page, there is access to the flag.php page, but, of course, there are no flag.php sources.
What could be the ways to get the value of this variable?

Answer 1

Variable value or file sources?
if variable then justvar_dump($flag);