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

wbFDXJQDQxQJzudOUlR, QEbsIDXJQDQxQsSYIutwU
DXJQDQxQ

nFgMXUzpStDAybiwm, aNJrXUzpStDjp
XUzpStD

IxQuXNNbwM, LvQcQuXNtYH

QuXN