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

SOLUTION: bAgSV

PROBLEM: QzJdafaGRLWEguLkOaw, brmPLBoaGRLWEguEaF

SOLUTION: aGRLWEgu

PROBLEM: DWOeyABVfIbElESyO, XMOLBVfIbElEBGGhOe

SOLUTION:
BVfIbElE