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

SOLUTION: JMpx

PROBLEM: yQCDWefwvrPP, RwoMDWefwhSxTR

SOLUTION: DWefw

PROBLEM: IGYiQKzmgpRPNcsNGu, TybafzgpRPNcsNqkSWePaL

SOLUTION:
gpRPNcsN