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

Ex Input:
fBpRXPkikQokGVeS, FwUbKXkikQokGos

Ex Output:
kikQokG


Ex Input:
ztkWLUJQXxP, fYluOkWLUJKDX

Ex Output:
kWLUJ


Ex Input:
vSFkHlYYclBaavj, lIFHlYYclBaWHbuuK

Ex Output:

HlYYclBa