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

Example Input: mXHhaCEIwqwEZcz, JZPXbYHhaCEIwZmna
Example Output: HhaCEIw

Example Input: dsngGP, KvnglB
Example Output: ng

Example Input: hGgUgMEHIQdIFDnjuZzueOj, LnvhDGroxMEHIQdIFDnOThPj
Example Output:
MEHIQdIFDn