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

fREVIdeTcakgFnwDWTVev, IbtXImseeTcakgFnwDYsKBAlux
eTcakgFnwD

GrvtMjEvRlmN, ifGOWMjEvRPSOZK
MjEvR

DlsenXqmLuhta, FgFjeGXqmLuhnNAx

XqmLuh