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

vSFxjd, AHFxpi
Fx

txJhzNeBj, qLJhzNesV
JhzNe

CnnZcJgADtKtsNwZyME, xvpnZcJgADtKXZ

nZcJgADtK