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

XwBMFIV, SNLBMFZQ
BMF

KvPFobZEGs, eKFobZEtnm
FobZE

XVdXgGmeTNFMYrhywmM, rFXgGmeTNFMddwBlQw

XgGmeTNFM