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

[Q]: BrDGrTD, PBHDGrDw
[A]: DGr


[Q]: yOGvgtAmwMwcIRtJ, cQtAmwMwcIRjfjO
[A]: tAmwMwcIR


[Q]: HpJDFLokeq, YCJDFLXzs
[A]:
JDFL