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

Ex Input:
XeQwOS, OuQwNR

Ex Output:
Qw


Ex Input:
wcJmSloqlddFOfv, szhUIAqzSloqlddFDJz

Ex Output:
SloqlddF


Ex Input:
ZSuMua, CtuMlX

Ex Output:

uM