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

Input: Consider Input: rCFrfkmXbSHK, mztfkmXwez

Output: fkmX


Input: Consider Input: QzJdafaGRLWEguLkOaw, brmPLBoaGRLWEguEaF

Output: aGRLWEgu


Input: Consider Input: sXyxYptuFQmE, lAZyxYptVPr


Output: yxYpt