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

Q: IQIHqbEhpVuNATp, GIJIHqbEhpzWb

A: IHqbEhp
****
Q: FgQsxN, UMQsIa

A: Qs
****
Q: wEhKdturG, miKdtuIL

A:
Kdtu
****