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

Example Input: TizkNtJUPHfhmGQ, enzehVkNtJUPHunpG
Example Output: kNtJUPH

Example Input: JIOKyo, oPOKsX
Example Output: OK

Example Input: OGcouTtttLEAeHyQqg, oDsJeuTtttLEAeoIRa
Example Output:
uTtttLEAe