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

Ex Input:
LudFxiaqbX, UWMPnFxiaqikiDx

Ex Output:
Fxiaq


Ex Input:
ktABEFESAVHZkkY, uMjxiESAVHZkZgWUte

Ex Output:
ESAVHZk


Ex Input:
tMkRfCQAVc, keokRfCQNGAe

Ex Output:

kRfCQ