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

BICndZkjoSidWivWATvtqsS, FzVWjoSidWivFaQhkRT
joSidWiv

sGrHRmELarByxp, cDCUnmELarBXbEfM
mELarB

meFTBKBR, MiWFTBOh

FTB