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

SOLUTION: FcxO

PROBLEM: xtCJGe, DXCJSw

SOLUTION: CJ

PROBLEM: pgZbMCyFUhkxDkCQQMDxTWKENg, ZgRQSxXfqEFUhkxDkCQQtEGgFUpSSL

SOLUTION:
FUhkxDkCQQ