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

Ex Input:
PivhPfah, XSghPfOi

Ex Output:
hPf


Ex Input:
cvRdSsuNwGVEwSSrowDpaOu, gFMcLKIeLwNwGVEwSSroUGskaoloqC

Ex Output:
NwGVEwSSro


Ex Input:
yiPNiEF, hBxPNiKz

Ex Output:

PNi