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

[EX Q]: HaIPcFXLhYDp, AdIPcFXtJdRE
[EX A]: IPcFX

[EX Q]: UQDJDbzqDxsMzUL, BxClJDbzqDxLxlngc
[EX A]: JDbzqDx

[EX Q]: eUytPOZmgV, IGNytPODxbc
[EX A]:
ytPO