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

SOLUTION: CjAWPH

PROBLEM: GnElFKBIoYmAdvz, GrElFKBIoMo

SOLUTION: ElFKBIo

PROBLEM: KsGPFcgIJL, vgozgNGPFcgIyXrsCj

SOLUTION:
GPFcgI