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

Example Input: dZJWBGoeoMepPoTg, pekBGoeoMeQP
Example Output: BGoeoMe

Example Input: QKlzsmHyBcC, snPtzsmHdMIv
Example Output: zsmH

Example Input: FUgTqRfqo, zJTqRzGA
Example Output:
TqR