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

Ex Input:
xfZYYDKEqoRRu, ztCeYYDKEqoPG

Ex Output:
YYDKEqo


Ex Input:
wrVsKN, mOVsWo

Ex Output:
Vs


Ex Input:
BXsTzYJs, TNsTzgPc

Ex Output:

sTz