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

PQSFjlnU, kTSFjMUh
SFj

wbFDXJQDQxQJzudOUlR, QEbsIDXJQDQxQsSYIutwU
DXJQDQxQ

HJajdyDDSAWtDjpX, RkHVyDDSAWtbMXi

yDDSAWt