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

Q: pYmzRnGPQVPrqPApKTyvaO, tNGPQVPrqPVTh

A: GPQVPrqP
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Q: OrcQOvMBhmwP, mnWrzcQOvMBnLwI

A: cQOvMB
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Q: NOixKUFmwRjg, yrKUFmGXg

A:
KUFm
****