can anyone help me to understand the solution of (http://codeforces.com/problemset/problem/682/D) problem.It's like longest common sub-sequence but there is a extra condition.I am trying to understand the recurrence relation.

problem C — Watto and Mechanism.... can anyone explain why i am getting TLE? my code is given below: 9867828.i think my code execute worst query in 3.6*10^11.can anyone tell me how can reduce this operation number?