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

Example Input: OYERnjubLFovtcS, FngzQJVGERnjubLFafmzq
Example Output: ERnjubLF

Example Input: eedZoMwKgDhdsgs, kMMwKgDLm
Example Output: MwKgD

Example Input: OvSoCuqjNxwvkCsXsAFR, VYjNxwvkCsXyMt
Example Output:
jNxwvkCsX