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

SOLUTION: SFj

PROBLEM: sRTQgRgRUjEooapKdR, vzsBgRUjEooLBkYeH

SOLUTION: gRUjEoo

PROBLEM: dqTdlzGLiWZSPrwR, BDVlzGLiWZvb

SOLUTION:
lzGLiWZ