instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
UTdardKNThdYrGKMqZPeg, mvrThdYrGKMlcCxBtak
answer:
ThdYrGKM


question:
zgJGhxLU, EwJGhedW
answer:
JGh


question:
JVVfatSNoowMSsujuswHIWovm, ZPTlgRGTtSNoowMSsuIM
answer:

tSNoowMSsu