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

Ex Input:
OyXwTWbLByC, yODnTWbLWYzc

Ex Output:
TWbL


Ex Input:
AxRSlkQfWHrdlgQG, iXIOrmlkQfWHTy

Ex Output:
lkQfWH


Ex Input:
kPRScxgg, TBRScxJk

Ex Output:

RScx