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

[EX Q]: IIbJjQKWaoGKHGgWPcy, uNoMWaoGKHGqbnjmYQ
[EX A]: WaoGKHG

[EX Q]: yKtQOhYvrJVH, HQsTQOhYvPP
[EX A]: QOhYv

[EX Q]: rusJezawZwZtq, VhqjRzawZwZeMXAB
[EX A]:
zawZwZ