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:
ChKUlYUTQQBjZMZkgEed, lmQQBjZMZkgdEf

Ex Output:
QQBjZMZkg


Ex Input:
SJIkEibGrqcrOBgGjYjJc, EervOGrqcrOBgGJZyx

Ex Output:

GrqcrOBgG