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

[EX Q]: euQWhCovKplukMYznXcD, XAfMhKdzhCovKplukMcMlSuBw
[EX A]: hCovKplukM

[EX Q]: XHqQIPw, brqQIkAt
[EX A]: qQI

[EX Q]: JAHnJJOpQSlopz, SQOnJJOpQSUZa
[EX A]:
nJJOpQS