In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.

[Q]: trHTzJpm, aCHTzVVA
[A]: HTz


[Q]: spGRUmIYuGl, qkqRUmItqU
[A]: RUmI


[Q]: zKQfvmiUSYBRFkCftbJPOgh, zerLJbPZSYBRFkCftsOUBnE
[A]:
SYBRFkCft