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

tmBlKUto, eFDBlKLy
BlK

KJswoapnXz, EQswoaFyH
swoa

DXERfjcHVGkTbuMxEewEdzf, ugzaGkTbuMxEeMLxdaXPI

GkTbuMxEe