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

[EX Q]: mJoHBJehHtkFS, ZMrDxHBJehHtxS
[EX A]: HBJehHt

[EX Q]: hcmMoVBhK, mdmMoVBjuT
[EX A]: mMoVB

[EX Q]: hiDQkVxMFrNd, DRnkVxMOwI
[EX A]:
kVxM