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

[EX Q]: PzXzvmYrlGZgOBk, iKnzvmYrlGZgOrs
[EX A]: zvmYrlGZgO

[EX Q]: wnIFoRQvMMKMAqpCQYncuWUTJs, bPMUKKxYRxQvMMKMAqpCmzAPPMD
[EX A]: QvMMKMAqpC

[EX Q]: aUCQyRpzoTCYKp, BzYrMwRpzoTCYGdJHSgL
[EX A]:
RpzoTCY