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

Q: SQNzngllNbOkKDK, MijfNzngllNDfWge

A: NzngllN
****
Q: RMurrwPjlfG, QBKrrwPDkTM

A: rrwP
****
Q: kUoqCMPFTqGE, guoqCMPkwJs

A:
oqCMP
****