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

Ex Input:
JIOKyo, oPOKsX

Ex Output:
OK


Ex Input:
NxgzLSzFGa, JvLzLSzsuj

Ex Output:
zLSz


Ex Input:
evqaVqDEQB, DzqaVqzBX

Ex Output:

qaVq