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

Ex Input:
MvALRGKkpALcKdhTtnm, neMkRGKkpALcKdcaxnXEPxW

Ex Output:
RGKkpALcKd


Ex Input:
JIOKyo, oPOKsX

Ex Output:
OK


Ex Input:
RzYodr, FyYoeO

Ex Output:

Yo