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

Ex Input:
KKebLWQCQzVIojj, nxQCQzVIopD

Ex Output:
QCQzVIo


Ex Input:
ssKUiWgGqsXYlFOOc, JDcVTmCgGqsXYlxYE

Ex Output:
gGqsXYl


Ex Input:
jgmLeWnBnzrcFlF, xfQEWnBnzje

Ex Output:

WnBnz