I have been trying to get my Python solution to Lamps in a Circle (Codeforces Global problem 8) to work. I was getting runtime errors on test 6, so I put in some code to print the error. On doing so my solution was accepted.

The accepted solution is https://codeforces.net/contest/1368/submission/84398375, the rejected one is https://codeforces.net/contest/1368/submission/84398296. The only difference is the code to catch the exception.

I initially saw this with PyPy3, but I get the same behaviour with Python 3.

Does anybody have any ideas on why this is happening?