In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

Input: Consider Input: lkFGXvTkKm, wwELXvTkcOnG

Output: XvTk


Input: Consider Input: BrDGrTD, PBHDGrDw

Output: DGr


Input: Consider Input: WdePYlrx, kqPYlmP


Output: PYl