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

Q: fdxgzAMP, xrcxgzYW

A: xgz
****
Q: jXqEDHTCxTiUAICWZJdpmYq, GBTCxTiUAICZKnLgZBXi

A: TCxTiUAIC
****
Q: QECPAHsg, bUfPAHOWb

A:
PAH
****