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

[EX Q]: CMrTXnTnTVaR, srnXnTnTDNULO
[EX A]: XnTnT

[EX Q]: KvPFobZEGs, eKFobZEtnm
[EX A]: FobZE

[EX Q]: TazMJnxrIUnaB, osZInxrIUnsWIf
[EX A]:
nxrIUn