In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

[EX Q]: PShMbsbexXGlpBuMMDZZS, sVqGxSexXGlpBxuHXoI
[EX A]: exXGlpB

[EX Q]: QvtDqzQiSknPbRCG, hVxHdqzQiSknPbumdpNIf
[EX A]: qzQiSknPb

[EX Q]: wujvihxzywqkuDlnLcxuFTbYZWUc, tlYirqkuDlnLcxuSFgoZPLJsg
[EX A]:
qkuDlnLcxu