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

[EX Q]: zRwQdelc, UdAUwQdejhe
[EX A]: wQde

[EX Q]: koIZvrJmfKCO, TBvrtjcWIZvrJmfKRZDOE
[EX A]: IZvrJmfK

[EX Q]: XiQjqmnEHzsyLeiogbUytTHyJ, jWXEHzsyLeiogVDxzonkTb
[EX A]:
EHzsyLeiog

