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

[EX Q]: dlzequypR, Puequqv
[EX A]: equ

[EX Q]: libDFDxIgRiglWfxMVRr, yMltDxIgRiglpms
[EX A]: DxIgRigl

[EX Q]: ckwXfnhLmsfoT, NoSuafnhLmup
[EX A]:
fnhLm