instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
tWJoKSOAuVhmsomA, emdmnBFJoKSOAuVzSgW
answer:
JoKSOAuV


question:
cxYVucnmEQopeWHrPJ, jNnOaYVucnmEQoSE
answer:
YVucnmEQo


question:
cUCQXEFSgRZjK, RYdvUQXEFSgRZVlwx
answer:

QXEFSgRZ