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

[Q]: ugDpSMRvHM, DDwSMRvxw
[A]: SMRv


[Q]: spUbdWDLWCeqr, vIuHkWDLWCQEPaz
[A]: WDLWC


[Q]: UphtIvaCftPxkMmiB, DnytIvaCftDR
[A]:
tIvaCft