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

Q: KKebLWQCQzVIojj, nxQCQzVIopD

A: QCQzVIo
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Q: OyrqfQQnzOFUzrkDM, iBkQQnzOFewhjvO

A: QQnzOF
****
Q: ciYRgGnBkwbhYdZrMBuECHuq, TbiXBppGrGnBkwbhYdZeXgNYQy

A:
GnBkwbhYdZ
****