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

Input: Consider Input: QqtCFzXHPNFXx, XECFzXHPSGwUuk

Output: CFzXHP


Input: Consider Input: dlzequypR, Puequqv

Output: equ


Input: Consider Input: vwDOQl, mYDOvs


Output: DO