instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
gfDDsblwUryUw, UWaRisblwUTqTM
answer:
sblwU


question:
cCDTMXjGMNikONun, jpcMXjGMNizBEWQzT
answer:
MXjGMNi


question:
SVNRFNlnZftWrVT, lFXidQxlPRFNlnZftWHyvNFlvSw
answer:

RFNlnZftW