instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
rvLoiycpZw, idcvoiycpcLyD
answer:
oiycp


question:
rlBoVyFsYqpmmQmelGBg, iKKaIyFsYqpmmWcrKn
answer:
yFsYqpmm


question:
cprFLvGrLdbN, UvVzrFLvGrLCmMcMU
answer:

rFLvGrL