Longest Increasing Subsequence

This question from Codeforces is based on LIS, but I dont understand how to solve it.

http://codeforces.com/contest/76/problem/F

please ask doubt related to the course you have taken and the problems you encountered during solving question given in your course.

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.