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

Example Input: AkYuNemHGBEDF, uluNemHGAycbWX
Example Output: uNemHG

Example Input: ATmVEtUuZOgsBUuL, UMUuZOgsBPVT
Example Output: UuZOgsB

Example Input: XyIuJBwculoZOMj, ErwculoZgS
Example Output:
wculoZ