Question: [General]

  Is there any issue with HTML format of problem statements?

Judge answer:

  PDF version of problems is more reliable. HTML have some issues due to caching mechanism.

Also be noted that the HTML version of problems A, D and F had minor changes and are updated.

Question: [Problem A]

  What is correct? "Defence" of "Defense"?

Judge answer:

  "Defense" is correct.

The problem description is fixed.