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

Example Input: OUNqomxFcLXhWdfB, gdqomxFcLHQPCu
Example Output: qomxFcL

Example Input: RGImMTISYdkjzMO, pmyfpImMTISYdatLBBFr
Example Output: ImMTISYd

Example Input: pFhTVXngL, wDArTVXnDc
Example Output:
TVXn