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

Ex Input:
CdRbREFMEDTXnEzgn, zHLEMMEDTXnEPH

Ex Output:
MEDTXnE


Ex Input:
ylyLVUjsmMrXMFAPDGIZsHq, cYymMrXMFAPjm

Ex Output:
mMrXMFAP


Ex Input:
sXXfYarze, UWfYajCT

Ex Output:

fYa