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

Ex Input:
lsNwypFwhKP, diEfLwypFwEKqCN

Ex Output:
wypFw


Ex Input:
BmwpAnWJ, klVwpAFw

Ex Output:
wpA


Ex Input:
gGvRNx, QhvRLz

Ex Output:

vR