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

[EX Q]: BpGFyhLez, DfFyhuJY
[EX A]: Fyh

[EX Q]: iYuUgULgqcAgd, kRNUgULgqFv
[EX A]: UgULgq

[EX Q]: UDpqiSrrOd, EYoRiSrrUPxp
[EX A]:
iSrr