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

SOLUTION: tthS

PROBLEM: XpFCxFOgTTNCnQzMnVPV, FMqzdOwgTTNCnQzedorxVPe

SOLUTION: gTTNCnQz

PROBLEM: MBfVCVMfKNJe, HSfgVMfKNNmYj

SOLUTION:
VMfKN