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

SOLUTION: Pufsa

PROBLEM: CUlMsvov, iflMsSRp

SOLUTION: lMs

PROBLEM: OyAQXHhVJxClnC, MKVHFAQXHhVJlBD

SOLUTION:
AQXHhVJ