instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
rcKVmDzwJKeK, uYqmDzwJKxkGi
answer:
mDzwJK


question:
BfCCzPNLBbwCoxMVAG, vhwNLBbwCbH
answer:
NLBbwC


question:
HGvdaPqWrTwXBz, zxLPqWrTwzDD
answer:

PqWrTw