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

Input: Consider Input: spGRUmIYuGl, qkqRUmItqU

Output: RUmI


Input: Consider Input: IGHhMfqLeBpnullsPInfBH, LTDBpnullsPIBynwCrCQ

Output: BpnullsPI


Input: Consider Input: iMwanJBuMdiZDL, kIafHeBuMdiZmKNA


Output: BuMdiZ