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

CwTYJWQbzEZkvcqKn, hBnhJWQbzEZkKmVM
JWQbzEZk

DwkTGsIXLfmjMV, VqRlMxtsSBkTGsIXLfmjbvI
kTGsIXLfmj

PrBxTTNYViJugNG, GpuxTTNYVhFuU

xTTNYV