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

SOLUTION: RUmI

PROBLEM: yjoJzBGdwfOhsceoOpoap, uSLMdBGdwfOhsIQHBijd

SOLUTION: BGdwfOhs

PROBLEM: YJUdJjkpjkEcgvZFHf, dkzzZrkBjkpjkEcgvCTqA

SOLUTION:
jkpjkEcgv