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

YRLHFm, odLHCI
LH

gfXPLNzsyfEotmHL, oJeXPLNzsyJuXP
XPLNzsy

mRVieYomZqJXaTDsShCyfPW, ifOAlnptmZqJXaTDsVMqY

mZqJXaTDs