instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
CkZOSZevST, bbZOSZIg
answer:
ZOSZ


question:
dZJWBGoeoMepPoTg, pekBGoeoMeQP
answer:
BGoeoMe


question:
koddLvYmRXDUuUnW, GnqDYGmmRXDUuUquAnf
answer:

mRXDUuU