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

[EX Q]: gWMyioGBRpwcXfr, AOQGBRpwcSccqBE
[EX A]: GBRpwc

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

[EX Q]: ULpbSWjcQYGL, LHJpbSWjcQYfJhUDo
[EX A]:
pbSWjcQY