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

Example Input: YcgVJVACcQE, JsJVACcSz
Example Output: JVACc

Example Input: FQAznAuFjoBKRKB, hPmtFFPnuAznAuFjoBKTgkeJyjcd
Example Output: AznAuFjoBK

Example Input: jjZPUiM, AfZPULT
Example Output:
ZPU