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

iMwanJBuMdiZDL, kIafHeBuMdiZmKNA
BuMdiZ

sJRFPufsaWXNeu, AePufsafc
Pufsa

FOngoZLtKNkyKbam, IhANBnoZLtKNHGM

oZLtKN