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

[EX Q]: fBpRXPkikQokGVeS, FwUbKXkikQokGos
[EX A]: kikQokG

[EX Q]: YcgVJVACcQE, JsJVACcSz
[EX A]: JVACc

[EX Q]: OvWbYBJux, QXuWbYBZUq
[EX A]:
WbYB