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

uHGHiARtdJbuG, OdZmiARtdrhC
iARtd

ocjsZZfSBBopDtgWUT, rWmgzsZZfSBBoGWQ
sZZfSBBo

zdHmuaJYtJGGAbykCmSyd, lXvAozYYtJGGAbyiXwen

YtJGGAby