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

Ex Input:
KTAFonizDqCVvucpJWrItdw, rfFonizDqCVvYbGhb

Ex Output:
FonizDqCVv


Ex Input:
DQBpdnwVDcnCDEWpD, gAtCdnwVDcnCYv

Ex Output:
dnwVDcnC


Ex Input:
xPAUoQGdHxgoYMrsEGw, vWGdHxgoYMrsiUuSRwqE

Ex Output:

GdHxgoYMrs