instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
UIjAMFDuxDDGkfQa, VdsHuxDDGkfZHZZ
answer:
uxDDGkf


question:
QeNePjbLBKbDOuAVTJtXL, xjPVOyPbLBKbDOuDsMSEF
answer:
bLBKbDOu


question:
nHEaXUUdsPGYqnCtVAefFD, CRUzqdsPGYqnCHxgCkPY
answer:

dsPGYqnC