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:
OrcQOvMBhmwP, mnWrzcQOvMBnLwI

Ex Output:
cQOvMB


Ex Input:
vfFigv, IPFiLe

Ex Output:

Fi