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

SOLUTION: BqdPcXfHot

PROBLEM: jXbgnl, lUbglP

SOLUTION: bg

PROBLEM: YOJKkskwXwWn, KNDKkskwXqY

SOLUTION:
KkskwX