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

Ex Input:
rcKVmDzwJKeK, uYqmDzwJKxkGi

Ex Output:
mDzwJK


Ex Input:
nXVXIEGP, fkXIEkU

Ex Output:
XIE


Ex Input:
WIvsQzGKVC, UqvsQzaO

Ex Output:

vsQz