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:
wnIFoRQvMMKMAqpCQYncuWUTJs, bPMUKKxYRxQvMMKMAqpCmzAPPMD
answer:
QvMMKMAqpC


question:
gltfmgrDSphPxsl, RTbRcrDSphPXzQ
answer:

rDSphP