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

Ex Input:
RpaZAvSnEBgGapIPQgw, wcwYsXvSnEBgGapIwoIWROB

Ex Output:
vSnEBgGapI


Ex Input:
wYhGWdRC, cFGWdHEy

Ex Output:
GWd


Ex Input:
zeeeWAnv, PTeeWuc

Ex Output:

eeW