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

Example Input: MSxTzCpiJAplpzSvLlNJS, oScCpiJAplpNVrqkn
Example Output: CpiJAplp

Example Input: xtCJGe, DXCJSw
Example Output: CJ

Example Input: WLxYozWEQZecS, DAOxYozWEQZeoKxolm
Example Output:
xYozWEQZe