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

[EX Q]: yhhzISsXKEbA, KlPrazISsXKzmrVBG
[EX A]: zISsXK

[EX Q]: SUgXyznbUQRpiLUTlRb, jlnwLTnbUQRpioUFyJ
[EX A]: nbUQRpi

[EX Q]: vmxLIypKXFU, LfxLIypKhNAmk
[EX A]:
xLIypK