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

Ex Input:
zfUPUDeKbCMQa, BkAJFJUDeKbCMZmkFu

Ex Output:
UDeKbCM


Ex Input:
WRfFDeZjIcpidmDxtaJcv, XMxWZjIcpidmlKga

Ex Output:
ZjIcpidm


Ex Input:
LgSRXQYabEBnvI, KqXvpoRXQYabEBaS

Ex Output:

RXQYabEB