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

CUxfOt, dyxfNp
xf

sRTQgRgRUjEooapKdR, vzsBgRUjEooLBkYeH
gRUjEoo

zPvaWrgpaixoxkR, RNXaWrgpaixoxcAbcaZQFx

aWrgpaixox