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

Input: Consider Input: sRpnJlgECTHh, JXfmNJlgECKyry

Output: JlgEC

Input: Consider Input: zqwhMdAdXQfQCAmVNaYZm, toYMIwQeadAdXQfQCAmLyheFOv

Output: dAdXQfQCAm

Input: Consider Input: lbiwoamlp, xniwoafb
Output: iwoa