OJ Board

Hello. I got TLE in last contest. I tried it using O(n^3) algorithm.
I've heard that there are O(n^2) and O(nlogn) algorithm.
I've thought of it since last contest, but I don't know about that.
Would you kindly give me some hints about O(n^2) or O(nlogn)?
Or you can PM me.

Thanks.

Hello. I want to know O(n^2) and O(n) algorithm about this problem.
Would you give me some hint?
Thanks