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

Input: Consider Input: FQAznAuFjoBKRKB, hPmtFFPnuAznAuFjoBKTgkeJyjcd

Output: AznAuFjoBK

Input: Consider Input: trHTzJpm, aCHTzVVA

Output: HTz

Input: Consider Input: xzPkTsYXokwJLXOJBnrwcFPvkpNRsX, GOasHwVCpZwJLXOJBnrwzwZA
Output: wJLXOJBnrw