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

[Q]: lMRuEThD, wqQRuEKp
[A]: RuE


[Q]: WFAPUCgVYbmZiFlacUzyv, xQFiekrgPUCgVYbmZUEtl
[A]: PUCgVYbmZ


[Q]: gUSjyNpLQuqePHpiIBY, GJogKqNlLQuqePHpBbINm
[A]:
LQuqePHp