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

Ex Input:
HKCoXQsLRtowYJ, PGRzNUQsLRtoLcqkn

Ex Output:
QsLRto


Ex Input:
ljwjMioOwfOltGBaE, TneNGsoOwfOlxnWWW

Ex Output:
oOwfOl


Ex Input:
DucJXi, IqcJia

Ex Output:

cJ