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

Answer: QsLRto


Question: jAinxmaQUrmu, jqeEnxmaQUrWlrEqW

Answer: nxmaQUr


Question: qczzCr, zDzzUI

Answer:
zz