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

Ex Input:
krnkpodgfpCKtfCqyzUbymWbxi, DydgSWpCKtfCqyzDaMsjqc

Ex Output:
pCKtfCqyz


Ex Input:
oWwqraAz, uxTqraonu

Ex Output:
qra


Ex Input:
IvMFOrJnkHlnJdi, XlKSTrJnkHlYC

Ex Output:

rJnkHl


