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

Ex Input:
NNpkdhvgT, BMkAkdhvrwV

Ex Output:
kdhv


Ex Input:
cZSEmdgP, YsSEmEIM

Ex Output:
SEm


Ex Input:
hSQiOzrEJqx, tDxYQiOzrFeY

Ex Output:

QiOzr