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

[EX Q]: TnbLNKnNSs, NhDLNKnNRd
[EX A]: LNKnN

[EX Q]: IKrQfT, crrQRg
[EX A]: rQ

[EX Q]: IUVTOEuQccbTzPumdQfUOosl, oHoZuQccbTzPuMW
[EX A]:
uQccbTzPu