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

Input: Consider Input: EyvnjbVLF, vqnjblzR

Output: njb

Input: Consider Input: xzMUdHcoYJFWLOILjrg, vCscoYJFWLzO

Output: coYJFWL

Input: Consider Input: ZOIYfkMmLnXV, irfkMmLEjbd
Output: fkMmL