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

SOLUTION: OK

PROBLEM: fBpRXPkikQokGVeS, FwUbKXkikQokGos

SOLUTION: kikQokG

PROBLEM: WMiZFjCvPgn, gqVFjCvPky

SOLUTION:
FjCvP