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

Ex Input:
QEEVsnbQIgrxaZmflaZ, dPSbljkdQIgrxaZmgVzMT

Ex Output:
QIgrxaZm


Ex Input:
yKtQOhYvrJVH, HQsTQOhYvPP

Ex Output:
QOhYv


Ex Input:
aQNRYWQpnodGtfJqXWrrkZyUpdaISk, eqTdGtfJqXWrrHZjiUCzEg

Ex Output:

dGtfJqXWrr