instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
BrDGrTD, PBHDGrDw
answer:
DGr

question:
BeEgLISxThm, UGLISxEtP
answer:
LISx

question:
vseVZkXsRBQqcSTNLBphRe, ETQkHRMFqkXsRBQqcSrv
answer:
kXsRBQqcS