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

Ex Input:
tmBlKUto, eFDBlKLy

Ex Output:
BlK


Ex Input:
wlFcxOHoXC, IWFcxOIWTk

Ex Output:
FcxO


Ex Input:
ReoQvrVhKaW, BGySoQvrVhyp

Ex Output:

oQvrVh