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

BfCCzPNLBbwCoxMVAG, vhwNLBbwCbH
NLBbwC

jJSSBmflUyrEMLjSycA, YkmujkSSBmflUyrKKJZ
SSBmflUyr

slSwCMhaQiLcJ, OFbErwCMhajrAu

wCMha