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

Ex Input:
WjyKtxKtEYjP, vuBZJZyKtxKtXRZs

Ex Output:
yKtxKt


Ex Input:
AeYjeKwZQillzpD, SnqviKwZQillrxuTB

Ex Output:
KwZQill


Ex Input:
NqPHWyYS, PhPHWIaA

Ex Output:

PHW