I am unable to solve the question https://www.hackerrank.com/contests/codeagon/challenges/jesse-and-two-strings-

The editorial is clear to me upto the point where i encounter the following statement After finding the LPS for the both the strings, we traverse through L(i,i)=Length of LPS,∀i=0...N−1 and see what all the middle characters can both the LPS's have. Can someone explain me this? Thanks.