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

Ex Input:
njzfcapS, JDzfcYQh

Ex Output:
zfc


Ex Input:
XEvxzelZaWRO, zXIelZaWBUn

Ex Output:
elZaW


Ex Input:
KzpDQnvXVnKLWu, pyqDQnvXVnSeSysH

Ex Output:

DQnvXVn