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

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


[Q]: QKlzsmHyBcC, snPtzsmHdMIv
[A]: zsmH


[Q]: rzsosx, OTsoUr
[A]:
so