Problem 4, week 1

Score “-1” means a major mistake, will bring penalty factor 0.8
Score “-0.5” means a minor mistake, will bring penalty factor 0.9.
Score “-0.6” means two different versions have been submitted twice, both with minor mistake(s), will bring penalty factor 0.95*0.9.
Score “-0.25” means a self-corrected minor mistake, will bring penalty factor 0.95.
Score “0” means that answer was submitted, but full solution wasn’t.

Positive number denotes the penalty factor (“1” = no penalty); penalties from the previous attempts have been applied, but the result is not multiplied with the base score of 0.9 (due to the publication of the first hints) or 0.8 (due to the publication of the second hints) .