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

SOLUTION: rmFRJYWLvZ

PROBLEM: TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK

SOLUTION: YjBCeUpy

PROBLEM: LrLDfQXxEfoV, UUfQXxbD

SOLUTION:
fQXx