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

SOLUTION: DsKQ

PROBLEM: trHTzJpm, aCHTzVVA

SOLUTION: HTz

PROBLEM: qMnjlfIsQRtUlPggCpHqu, gfVndMwYDIsQRtUlPgqBJKCX

SOLUTION:
IsQRtUlPg