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

SOLUTION: xf

PROBLEM: GrvtMjEvRlmN, ifGOWMjEvRPSOZK

SOLUTION: MjEvR

PROBLEM: KLXdqCiafvVIuMaacELlQK, zYvKVdWSfvVIuMaaOyQSp

SOLUTION:
fvVIuMaa