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

uqazNuZhdJhw, KbnrzNuZhBdp
zNuZh

spGRUmIYuGl, qkqRUmItqU
RUmI

FYewDXnaJHnSjeVgBeBVZr, hIjATuuuDXnaJHnSjFHMtOjQI

DXnaJHnSj