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

jFVaEHbMrrkW, ekfVaEHbPnBnM
VaEHb

SFQHJlK, dHfQHJoUC
QHJ

BQjLgJfTegmUnHjLCUuduoM, uRBlkegmUnHjLFOi

egmUnHjL