instruction:
In this task, you are given two strings A, B. Find the longest common substring in the strings A and B.
question:
QzJdafaGRLWEguLkOaw, brmPLBoaGRLWEguEaF
answer:
aGRLWEgu


question:
oKZCAErEMqzODnkcNqxVdoBOC, yHzRJuSqzODnkcNqxExr
answer:
qzODnkcNqx


question:
IomFPlXdMidSLXNQo, NCPdBpFPlXdMidPAuO
answer:

FPlXdMid