TASK DEFINITION: In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
PROBLEM: faHRBWyXsYzYmHQyy, aHTyXsYzYeXBFV

SOLUTION: yXsYzY

PROBLEM: vytthSjj, XVttthSFAvk

SOLUTION: tthS

PROBLEM: ERBgRMbF, DWzMBgRMZu

SOLUTION:
BgRM