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

SOLUTION: qzQiSknPb

PROBLEM: pYmzRnGPQVPrqPApKTyvaO, tNGPQVPrqPVTh

SOLUTION: GPQVPrqP

PROBLEM: eKmvfGpRGCImRv, nzvfGpRGgj

SOLUTION:
vfGpRG