In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
--------
Question: YRNpKFPGzUsgCOBJgbVG, TdEpMngFPGzUsgCOZykYRrLp

Answer: FPGzUsgCO


Question: CCzKRbuEAmN, qTLzKRbuhEqq

Answer: zKRbu


Question: HKOqWiVE, fLOOqWRG

Answer:
OqW