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

[Q]: zgJGhxLU, EwJGhedW
[A]: JGh


[Q]: IGHhMfqLeBpnullsPInfBH, LTDBpnullsPIBynwCrCQ
[A]: BpnullsPI


[Q]: OBOGEJ, RUOGuJ
[A]:
OG