instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
KKrCLvJKRoyV, WDeLvJKCBdS
answer:
LvJK


question:
XmiLktrUjJDOCJ, UIKrUjJDOQsR
answer:
rUjJDO


question:
fsvCyIYlhQJMCEilHU, PeFYOSrhQJMCEilRSp
answer:

hQJMCEil