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

Ex Input:
QjDQjzAIsnYgNmmetl, vyqDQjzAIsnNajYEheP

Ex Output:
DQjzAIsn


Ex Input:
HHJAHyvNCGmJEljWrjvHOqf, msPVEbNCGmJEljsKRX

Ex Output:
NCGmJElj


Ex Input:
RFqiXhLKOm, RaXhLKfNQ

Ex Output:

XhLK