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

SOLUTION: awup

PROBLEM: wlFcxOHoXC, IWFcxOIWTk

SOLUTION: FcxO

PROBLEM: FEexzt, tkexRm

SOLUTION:
ex