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

Ex Input:
HHJAHyvNCGmJEljWrjvHOqf, msPVEbNCGmJEljsKRX

Ex Output:
NCGmJElj


Ex Input:
UZbmGVDzIaf, qfHwqGVDzIsd

Ex Output:
GVDzI


Ex Input:
niFLRdkmOC, GvXLRdkjF

Ex Output:

LRdk