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

Ex Input:
SJIkEibGrqcrOBgGjYjJc, EervOGrqcrOBgGJZyx

Ex Output:
GrqcrOBgG


Ex Input:
UtUSmsOI, dCUSmGoQ

Ex Output:
USm


Ex Input:
FqxfnyDAFsnr, VnvhtfnyDAFxmGite

Ex Output:

fnyDAF