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

[Q]: BmwpAnWJ, klVwpAFw
[A]: wpA


[Q]: wkVVZREWhcSCpvCTB, ZQWhcSCpvCDVUY
[A]: WhcSCpvC


[Q]: YisSiZsBKjBbWv, WIKfiZsBKjBORx
[A]:
iZsBKjB