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

[EX Q]: kUoqCMPFTqGE, guoqCMPkwJs
[EX A]: oqCMP

[EX Q]: tWJoKSOAuVhmsomA, emdmnBFJoKSOAuVzSgW
[EX A]: JoKSOAuV

[EX Q]: tzvqsQPOTJYJkmqXs, iOnzyKRnqsQPOTJYxzHl
[EX A]:
qsQPOTJY