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

[EX Q]: GnElFKBIoYmAdvz, GrElFKBIoMo
[EX A]: ElFKBIo

[EX Q]: CxosNa, ikosdx
[EX A]: os

[EX Q]: PHGKdpKKzqvb, QwBdpKKhk
[EX A]:
dpKK