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

[EX Q]: wbFDXJQDQxQJzudOUlR, QEbsIDXJQDQxQsSYIutwU
[EX A]: DXJQDQxQ

[EX Q]: fdinRdwwlntwqzYGhV, ZefonRdwwlntoWQbh
[EX A]: nRdwwlnt

[EX Q]: objOlZLGVxFaGnnutzDvj, xQLVnVxFaGnnutHnAnf
[EX A]:
VxFaGnnut