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

VGRjWGHRcBdFmkVg, eSwqALQXWGHRcBdFsDXCM
WGHRcBdF

TvNVpHLPYjBCeUpyxlzFZ, tgKdPKVYjBCeUpyPK
YjBCeUpy

cpFEwIsNjcmI, HzEwIsNVZx

EwIsN