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

OVVkkdeHoFlyNROyCP, zFVUJbvkkdeHoFlysF
kkdeHoFly

IzwlZDJSEFPxfIud, xwWSYwlZDJSEFPbvSXTlS
wlZDJSEFP

QdgpvgfCtQJVx, DlbugpvgfCtSKFGVGM

gpvgfCt