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

SOLUTION: xr

PROBLEM: EOacPYivmmUlYenynBqAwx, MoZWMOeXmUlYenynBEendWg

SOLUTION: mUlYenynB

PROBLEM: lpgzKRSo, eDzKRkQz

SOLUTION:
zKR