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

SOLUTION: UuZOgsB

PROBLEM: JqdTDnZqSuSVcMsx, TEtDDnZqSuZa

SOLUTION: DnZqSu

PROBLEM: yiNRTw, ZuNRsR

SOLUTION:
NR