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

Example Input: jXqEDHTCxTiUAICWZJdpmYq, GBTCxTiUAICZKnLgZBXi
Example Output: TCxTiUAIC

Example Input: DQVkAbWTTPhoBx, TeWTTPhonxcIKL
Example Output: WTTPho

Example Input: FSOcBzPJS, rvJcBzcsb
Example Output:
cBz