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

Ex Input:
IIbJjQKWaoGKHGgWPcy, uNoMWaoGKHGqbnjmYQ

Ex Output:
WaoGKHG


Ex Input:
UCbReSfuLcbzmBCl, snQRReSfuLcbzmjqVPSdpp

Ex Output:
ReSfuLcbzm


Ex Input:
znWaJypjzLzjcLheqAK, ZtHJypjzLzjmvEEkP

Ex Output:

JypjzLzj