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

Ex Input:
VByrCcgcxCfPGDFqIWGloQZTMQf, OqfPGDFqIWGlalTCCkKkMf

Ex Output:
fPGDFqIWGl


Ex Input:
HaIPcFXLhYDp, AdIPcFXtJdRE

Ex Output:
IPcFX


Ex Input:
MCeVIBlpZakNTly, FKxAgVIBlpZakmqFCIus

Ex Output:

VIBlpZak