The contest hosted yesterday by IIT Gandhinagar had wrong test cases in one of the problems. The contraints as mentioned in the problem statement were not followed as a result of which many of us were getting Runtime error or wrong answer. The problem link is and there are definitely test cases where Zi>k as I tried to submit it after the contest was over and was able to pass keeping in mind that Zi>k. I even asked for a clarification in the comments section of the problem but there was no reply from the problem setters.
See my comment link.
Now I request @admin to take some action against the contest organizer.