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

SOLUTION: chk

PROBLEM: wNiHcaiUPHnjp, aSTmjcaiUPHFzOu

SOLUTION: caiUPH

PROBLEM: imvRqhBClDoUGlC, jRpwBClDoUMfKOfd

SOLUTION:
BClDoU