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

SOLUTION: xsZ

PROBLEM: QeNePjbLBKbDOuAVTJtXL, xjPVOyPbLBKbDOuDsMSEF

SOLUTION: bLBKbDOu

PROBLEM: QbonWeRUxEzufG, uXUTaNronWeRUxreVA

SOLUTION:
onWeRUx