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

[EX Q]: hRVyvwHqnN, geHeyvwHqiBiYJ
[EX A]: yvwHq

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

[EX Q]: ODzWuwRSm, XKTWuwvR
[EX A]:
Wuw