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

[EX Q]: KJswoapnXz, EQswoaFyH
[EX A]: swoa

[EX Q]: BmxgSFWBlVX, kGgKrgSFWBlGunFcZ
[EX A]: gSFWBl

[EX Q]: hZVHEQ, BoVHZm
[EX A]:
VH