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

Input: Consider Input: RtOkkgLvhgfGlX, vCOkgLvhzOa

Output: kgLvh


Input: Consider Input: uRLpAWCotLmxcSmKyvo, laotLmxcSmKyBwVfJB

Output: otLmxcSmKy


Input: Consider Input: LcpTIwilZc, lbGOTpTIwiBLr


Output: pTIwi