I am facing a really weird fast execution time on Codeforces on submission 75468775. On test #6, the code runs for 1153 ms on Codeforces servers, but when I run it on my own computer, it takes me 5682 ms to run! Yes there is difference on hardware of course, but it runs about 5 times faster on Codeforces! I am wondering if there is any optimization on Codeforces servers or compile instructions which makes it run as fast as this?

UPD: That is actually because of -O2 compile flag. Never knew it affects the running time as much as making it run 5 times faster.