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

SOLUTION: PUCgVYbmZ

PROBLEM: JqdTDnZqSuSVcMsx, TEtDDnZqSuZa

SOLUTION: DnZqSu

PROBLEM: kuqtptRlzhNZEXmrXrI, mOlzhNZEXaubTe

SOLUTION:
lzhNZEX