instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
YHLJZrFQ, aSLJZQuo
answer:
LJZ


question:
vMsEJRoLkWcmkuwNRz, ZmoLkWcmVZiBv
answer:
oLkWcm


question:
tvtPkCEx, EUtPkkLa
answer:

tPk