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

Ex Input:
UZbmGVDzIaf, qfHwqGVDzIsd

Ex Output:
GVDzI


Ex Input:
umXfmRnUgALpFAqBaKfNfo, aOAXWnUgALpFAqBmNpTCdj

Ex Output:
nUgALpFAqB


Ex Input:
MriFNpGM, yaiFNduk

Ex Output:

iFN