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

[EX Q]: LudFxiaqbX, UWMPnFxiaqikiDx
[EX A]: Fxiaq

[EX Q]: wXGerDNhSNnCCedyzskswVnh, BfFNhSNnCCedybrUbI
[EX A]: NhSNnCCedy

[EX Q]: RxrNdBqkldJ, mEHzNdBqYxG
[EX A]:
NdBq