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

[Q]: yQCDWefwvrPP, RwoMDWefwhSxTR
[A]: DWefw


[Q]: ZRjPgqbLL, uIsmPgqbBB
[A]: Pgqb


[Q]: BpXwnnkuSCnBNAhi, AFuEsXwnnkuSCnkRZ
[A]:
XwnnkuSCn