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

[EX Q]: QECPAHsg, bUfPAHOWb
[EX A]: PAH

[EX Q]: UIjAMFDuxDDGkfQa, VdsHuxDDGkfZHZZ
[EX A]: uxDDGkf

[EX Q]: VBQcfUAIbLYlnd, hGSRfUAIbLYPPgcVO
[EX A]:
fUAIbLY