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

SOLUTION: nz

PROBLEM: EyvnjbVLF, vqnjblzR

SOLUTION: njb

PROBLEM: lrBJDRkT, jmBJDrI

SOLUTION:
BJD