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

[EX Q]: JqdTDnZqSuSVcMsx, TEtDDnZqSuZa
[EX A]: DnZqSu

[EX Q]: HKqfdEvqDuGhWByFlzIEeYh, VVaZfkLCMuGhWByFlzIOZaXbMCA
[EX A]: uGhWByFlzI

[EX Q]: wUWwrctcyxRkEOkkuhEywdiRHy, ZnNQeqxRkEOkkuhECWBWqmzgD
[EX A]:
xRkEOkkuhE