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

[Q]: RtAchtNymcswVk, FWRuRchtNymcswUkoERHyML
[A]: chtNymcsw


[Q]: BICndZkjoSidWivWATvtqsS, FzVWjoSidWivFaQhkRT
[A]: joSidWiv


[Q]: MVUhvVrMQDlmKCHBX, xZrMQDlmGn
[A]:
rMQDlm