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

Example Input: esIMEOgV, tNIMEybb
Example Output: IME

Example Input: OUNqomxFcLXhWdfB, gdqomxFcLHQPCu
Example Output: qomxFcL

Example Input: ksOwEM, ZBOwXq
Example Output:
Ow