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

[EX Q]: iMwanJBuMdiZDL, kIafHeBuMdiZmKNA
[EX A]: BuMdiZ

[EX Q]: vFuggVITQuctFG, hdCIWWuuggVITQwr
[EX A]: uggVITQ

[EX Q]: NHZkUROjCh, DFDZkUROuUI
[EX A]:
ZkURO