instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
CwTYJWQbzEZkvcqKn, hBnhJWQbzEZkKmVM
answer:
JWQbzEZk

question:
JAfPtjqqUYMD, cpXItjqqFN
answer:
tjqq

question:
MrRPUO, epRPga
answer:
RP