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

Ex Input:
wYhGWdRC, cFGWdHEy

Ex Output:
GWd


Ex Input:
HEVqGddewrNqiZ, iyvlddewrNXr

Ex Output:
ddewrN


Ex Input:
mJqRGS, BrqRnj

Ex Output:

qR