in the N-queens problem, we've encountered a case where the Tester script misbehaves: a student used a global variable which counts the number of solutions for an N-sized board. when running the tester on several board-sizes, the global variable did not re-initialize to zero, causing it to sum the number of solutions across different board-sizes. the outcome: the tester received the right answer for the first board-size tested, but a wrong answer for all the following tests.
Since the use of global variables was allowed in this question we decided not to subtract any points. if something along the same lines happened in your code as well, please submit an appeal and the points deducted will be restored.
this is of course one of the dangers of using global variables - you never know who else is using them! please be careful whenever using global variables!
have a good weekend,
the course staff.