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

Ex Input:
STvKOHq, XMGvKOdyM

Ex Output:
vKO


Ex Input:
JqdTDnZqSuSVcMsx, TEtDDnZqSuZa

Ex Output:
DnZqSu


Ex Input:
UiBRVxGPfv, fPEGRVxGFUaQ

Ex Output:

RVxG