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

Ex Input:
OjQHcFUCflYUptUPqYKVomn, GXHcFUCflYUpSSTrQ

Ex Output:
HcFUCflYUp


Ex Input:
gTjTwC, OUjTgM

Ex Output:
jT


Ex Input:
atDgsOWuP, UJMgsOrwj

Ex Output:

gsO