instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
rlBoVyFsYqpmmQmelGBg, iKKaIyFsYqpmmWcrKn
answer:
yFsYqpmm

question:
uDaqoOpUtLDdTGTO, ncIgBjDPqoOpUtLDdTNtiEyarDO
answer:
qoOpUtLDdT

question:
BXotjIKIaCBxmjEYToMQzgs, UtXywCBxmjEYToMwNcLQO
answer:
CBxmjEYToM