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

[EX Q]: fdinRdwwlntwqzYGhV, ZefonRdwwlntoWQbh
[EX A]: nRdwwlnt

[EX Q]: YlhtTQgHiffTbIbBrcHMqFKCdWz, HyregFgMffTbIbBrcHYUnnQvGlx
[EX A]: ffTbIbBrcH

[EX Q]: WEvadgbt, OYadgngq
[EX A]:
adg