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

[EX Q]: TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK
[EX A]: YjBCeUpy

[EX Q]: aZcGMvzBhazkCIFqpVe, AOljBvzBhazkWXeTuA
[EX A]: vzBhazk

[EX Q]: GybpeeDjtPzRzSmnKBK, IhziypeeDjtPzRziCJkVHiGYd
[EX A]:
peeDjtPzRz