You can't request more than 20 challenges without solving them. Your previous challenges were flushed.

Comparison

Simple comparison between r.cost and r.walk posted here.

Reply

The content of this field is kept private and will not be shown publicly.
  • Allowed HTML tags: <div> <img> <a> <em> <strong> <cite> <code> <ul> <ol> <li> <dl> <dt> <dd>
  • Lines and paragraphs break automatically.

More information about formatting options

CAPTCHA
This question is for testing whether you are a human visitor and to prevent automated spam submissions.
Image CAPTCHA
Copy the characters (respecting upper/lower case) from the image.