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

[EX Q]: cjDuPZOHjystHnF, okWVdUDuPZOHjSCaEecP
[EX A]: DuPZOHj

[EX Q]: fREVIdeTcakgFnwDWTVev, IbtXImseeTcakgFnwDYsKBAlux
[EX A]: eTcakgFnwD

[EX Q]: HUYGCZuBCTaDzIdAt, amPnuBCTaDzJRw
[EX A]:
uBCTaDz