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

[EX Q]: dReySjyqecU, loSjyqiRl
[EX A]: Sjyq

[EX Q]: HXYkGv, GCYksu
[EX A]: Yk

[EX Q]: sGFKxFyxtICApjLxhGxJtErJN, AUnItIktICApjLxhGjXhIS
[EX A]:
tICApjLxhG