Can someone point out the mistake in my approach... Problem Link Code

https://www.spoj.com/problems/ONEXLIS/

i have been trying to solve the problem for a long time...but couldnt come up with a proper approach... My approach(ig wrong) : when we consider a sequence to be lis, the elements before the last element must have lds(longest strictly decreasing subsequence) > 1; however im unable to implement the idea; any help would be appreciated.

Hi everyone, I have created a gym with some cool binary search problems which might be helpful to some of you and will surely teach you something. link : https://mirror.codeforces.com/contestInvitation/210a7cea8bc7733fc8e65f2a8899b01837ee57e4

can anyone provide me with a mashup or gym link which have dp or graph problems that helped you strengthen these topics.