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

[EX Q]: wbdHVigIkjNkuAmbr, iSgIkjNkQYyn
[EX A]: gIkjNk

[EX Q]: TizkNtJUPHfhmGQ, enzehVkNtJUPHunpG
[EX A]: kNtJUPH

[EX Q]: ixlHvfiZPNfcQVSvPnEd, vzebVrlHvfiZPNfUORHB
[EX A]:
lHvfiZPNf