I thought it was 7 without the change of performance to 10^8, but I did that because many solutions passed in 8+ seconds. IDK about that probably no.

That's how I feel too; sorry if this is a newbie-ish question, but is there a way to change its kyu so 7-8 kyu people don't feel discouraged after not being able to solve this problem?

Also, I wasn't the one who chose the rank.

Yes, probably because of the performance requirements? Some solutions pass in like 7-8 secs, but others pass in 1-2 secs. I wanted everyone to have an efficient solution, so that is why, but some still take very long;-(