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

Input: Consider Input: PQSFjlnU, kTSFjMUh

Output: SFj


Input: Consider Input: rCFrfkmXbSHK, mztfkmXwez

Output: fkmX


Input: Consider Input: DLAHzwcHPvAFP, MYEbxdKAHzwcHPvAGjS


Output: AHzwcHPvA