instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
oCtWZYdkvZ, pkktWZYdEHMW
answer:
tWZYd


question:
WTnsmP, INnsIM
answer:
ns


question:
cqpHlnmk, MtLpHlngcd
answer:

pHln