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

Example Input: TdvkBvVyJcSdYGGPfnyml, rIvIvVyJcSdYhtxG
Example Output: vVyJcSdY

Example Input: IQIHqbEhpVuNATp, GIJIHqbEhpzWb
Example Output: IHqbEhp

Example Input: fgizCvrL, XszizCvPut
Example Output:
izCv