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

Example Input: HaIPcFXLhYDp, AdIPcFXtJdRE
Example Output: IPcFX

Example Input: IzwlZDJSEFPxfIud, xwWSYwlZDJSEFPbvSXTlS
Example Output: wlZDJSEFP

Example Input: ljwjMioOwfOltGBaE, TneNGsoOwfOlxnWWW
Example Output:
oOwfOl