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

XbjDHRCWxdPbhibUKn, SrpuPDHRCWxdPbKPWEXNWbZ
DHRCWxdPb

GnElFKBIoYmAdvz, GrElFKBIoMo
ElFKBIo

ksUFylVdBojUbWdVxCBw, diVFBojUbWdVxjdvc

BojUbWdVx