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

[EX Q]: QlJnxO, BLJnCQ
[EX A]: Jn

[EX Q]: MSxTzCpiJAplpzSvLlNJS, oScCpiJAplpNVrqkn
[EX A]: CpiJAplp

[EX Q]: fzykIHqIYzGAM, YhOTgOHqIYzGbRwqda
[EX A]:
HqIYzG