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

Ex Input:
aiqZheFuLtXAGRCGNBTAX, ssnVdztXAGRCGNBTIqmSJLZcy

Ex Output:
tXAGRCGNBT


Ex Input:
tftBHoDOYxCoTHVf, qhHoDOYxfUU

Ex Output:
HoDOYx


Ex Input:
CzgqymdCtnHO, SkpetygqymdCtqJn

Ex Output:

gqymdCt