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

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


[Q]: fVEFJa, WtEFYK
[A]: EF


[Q]: CedcKYCoOCHgzWKXmpjpKHthinRJJ, ZYLewmKjCHgzWKXmpjLmouOLp
[A]:
CHgzWKXmpj