instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
dlzequypR, Puequqv
answer:
equ


question:
osmJJcZlDAXBgJFsJKa, rzPNlDAXBgJYrgXlH
answer:
lDAXBgJ


question:
FjohtyBUApMcKlZpoj, yQBBUApMcKgMXUt
answer:

BUApMcK