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

Ex Input:
rlBoVyFsYqpmmQmelGBg, iKKaIyFsYqpmmWcrKn

Ex Output:
yFsYqpmm


Ex Input:
rCFrfkmXbSHK, mztfkmXwez

Ex Output:
fkmX


Ex Input:
AGlriYPqpXVPFnChZvg, QXufNTlqpXVPFnCekk

Ex Output:

qpXVPFnC