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

Ex Input:
OyrqfQQnzOFUzrkDM, iBkQQnzOFewhjvO

Ex Output:
QQnzOF


Ex Input:
ktABEFESAVHZkkY, uMjxiESAVHZkZgWUte

Ex Output:
ESAVHZk


Ex Input:
LoGAsKZNV, BKAsKMrN

Ex Output:

AsK